You can define the value for any layout property, paint property, or filter as an expression.

An expression defines a formula for computing the value of the property using the operators described below. The expression operators provided by Mapbox GL include:

Mathematical operators for performing arithmetic and other operations on numeric values
Logical operators for manipulating boolean values and making conditional decisions
String operators for manipulating strings
Data operators for providing access to the properties of source features
Camera operators for providing access to the parameters defining the current map view

Expressions are represented as JSON arrays. The first element of an expression array is a string naming the expression operator, for example "*" or "case". Elements that follow (if any) are the arguments to the expression. Each argument is either a literal value (a string, number, boolean, or null), or another expression array.


[expression_name, argument_0, argument_1, ...]

TUTORIAL

Get started with Mapbox GL JS expressions

Learn how to write expressions in Mapbox GL JS to style custom data based on a data property and by zoom level.

Data expressions

A data expression is any expression that accesses feature data – that is, any expression that uses one of the data operators: get, has, id, geometry-type, properties, or feature-state. Data expressions allow a feature's properties or state to determine its appearance. They can be used to differentiate features within the same layer and to create data visualizations.


{
    "circle-color": [
        "rgb",
        // red is higher when feature.properties.temperature is higher
        ["get", "temperature"],
        // green is always zero
        0,
        // blue is higher when feature.properties.temperature is lower
        ["-", 100, ["get", "temperature"]]
    ]
}

This example uses the get operator to get the temperature value of each feature. That value is used to compute arguments to the rgb operator, defining a color in terms of its red, green, and blue components.

Data expressions are allowed as the value of the filter property, and as values for most paint and layout properties. However, some paint and layout properties do not yet support data expressions. The level of support is indicated by the "data-driven styling" row of the "SDK Support" table for each property. Data expressions with the feature-state operator are allowed only on paint properties.

Camera expressions

A camera expression is any expression that uses the zoom operator. These expressions change the appearance of a layer with the map's zoom level. Camera expressions can be used to create the appearance of depth and to control data density.


{
    "circle-radius": [
        "interpolate", ["linear"], ["zoom"],
        // zoom is 5 (or less) -> circle radius will be 1px
        5, 1,
        // zoom is 10 (or greater) -> circle radius will be 5px
        10, 5
    ]
}

This example uses the interpolate operator to define a linear relationship between zoom level and circle size using a set of input-output pairs. In this case, the expression indicates that the circle radius should be 1 pixel when the zoom level is 5 or below, and 5 pixels when the zoom is 10 or above. Between the two zoom levels, the circle radius will be linearly interpolated between 1 and 5 pixels

You can use camera expressions anywhere an expression may be used. When you use a camera expression as the value of a layout or paint property, it must be in one of the following forms:


[ "interpolate", interpolation, ["zoom"], ... ]

Or:


[ "step", ["zoom"], ... ]

Or:


[
    "let",
    ... variable bindings...,
    [ "interpolate", interpolation, ["zoom"], ... ]
]

Or:


[
    "let",
    ... variable bindings...,
    [ "step", ["zoom"], ... ]
]

That is, in layout or paint properties, ["zoom"] may appear only as the input to an outer interpolate or step expression, or such an expression within a let expression.

There is an important difference between layout and paint properties in the timing of camera expression evaluation:

Paint property camera expressions are re-evaluated whenever the zoom level changes, even fractionally. For example, a paint property camera expression will be re-evaluated continuously as the map moves between zoom levels 4.1 and 4.6.
Layout property camera expressions are evaluated only at integer zoom levels. It will not be re-evaluated as the zoom changes from 4.1 to 4.6 – only if it goes above 5 or below 4.

Composition

A single expression can use a mix of data operators, camera operators, and other operators. Such composite expressions allows a layer's appearance to be determined by a combination of the zoom level and individual feature properties.


{
    "circle-radius": [
        "interpolate", ["linear"], ["zoom"],
        // when zoom is 0, set each feature's circle radius to the value of its "rating" property
        0, ["get", "rating"],
        // when zoom is 10, set each feature's circle radius to four times the value of its "rating" property
        10, ["*", 4, ["get", "rating"]]
    ]
}

An expression that uses both data and camera operators is considered both a data expression and a camera expression, and must adhere to the restrictions described above for both.

Type system

The input arguments to expressions, and their result values, use the same set of types as the rest of the style specification: boolean, string, number, color, and arrays of these types. Furthermore, expressions are type safe: each use of an expression has a known result type and required argument types, and the SDKs verify that the result type of an expression is appropriate for the context in which it is used. For example, the result type of an expression in the filter property must be boolean, and the arguments to the + operator must be numbers.

When working with feature data, the type of a feature property value is typically not known ahead of time by the SDK. To preserve type safety, when evaluating a data expression, the SDK will check that the property value is appropriate for the context. For example, if you use the expression ["get", "feature-color"] for the circle-color property, the SDK will verify that the feature-color value of each feature is a string identifying a valid color. If this check fails, an error will be indicated in an SDK-specific way (typically a log message), and the default value for the property will be used instead.

In most cases, this verification will occur automatically wherever it is needed. However, in certain situations, the SDK may be unable to automatically determine the expected result type of a data expression from surrounding context. For example, it is not clear whether the expression ["<", ["get", "a"], ["get", "b"]] is attempting to compare strings or numbers. In situations like this, you can use one of the type assertion expression operators to indicate the expected type of a data expression: ["<", ["number", ["get", "a"]], ["number", ["get", "b"]]]. A type assertion checks that the feature data matches the expected type of the data expression. If this check fails, it produces an error and causes the whole expression to fall back to the default value for the property being defined. The assertion operators are array, boolean, number, and string.

Expressions perform only one kind of implicit type conversion: a data expression used in a context where a color is expected will convert a string representation of a color to a color value. In all other cases, if you want to convert between types, you must use one of the type conversion expression operators: to-boolean, to-number, to-string, or to-color. For example, if you have a feature property that stores numeric values in string format, and you want to use those values as numbers rather than strings, you can use an expression such as ["to-number", ["get", "property-name"]].

If an expression accepts an array argument and the user supplies an array literal, that array must be wrapped in a literal expression (see the examples below). When GL-JS encounters an array in a style-spec property value, it will assume that the array is an expression and try to parse it; the library has no way to distinguish between an expression which failed validation and an array literal unless the developer makes this distinction explicit with the literal operator. The literal operator is not necessary if the array is returned from a sub-expression, for example ["in", 1, ["get", "myArrayProp"]].


// will throw an error
{
    "circle-color": ["in", 1, [1, 2, 3]]
}

// will work as expected
{
    "circle-color": ["in", 1, ["literal", [1, 2, 3]]]
}

Expression reference

Types

You can use type expressions to test and convert between different data types like strings, numbers, and boolean values.

Often, such tests and conversions are unnecessary, but they may be necessary in some expressions where the type of a certain sub-expression is ambiguous. They can also be useful in cases where your feature data has inconsistent types; for example, you could use to-number to make sure that values like "1.5" (instead of 1.5) are treated as numeric values.

array

Asserts that the input is an array (optionally with a specific item type and length). If, when the input expression is evaluated, it is not of the asserted type, then this assertion will cause the whole expression to be aborted.

Syntax


["array", value]: array


["array", type: "string" | "number" | "boolean", value]: array<type>


["array",
    type: "string" | "number" | "boolean",
    N: number (literal),
    value
]: array<type, N>

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

boolean

Asserts that the input value is a boolean. If multiple values are provided, each one is evaluated in order until a boolean is obtained. If none of the inputs are booleans, the expression is an error.

Syntax


["boolean", value]: boolean


["boolean", value, fallback: value, fallback: value, ...]: boolean

Example: Create a hover effect

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

collator

Returns a collator for use in locale-dependent comparison operations. The case-sensitive and diacritic-sensitive options default to false. The locale argument specifies the IETF language tag of the locale to use. If none is provided, the default locale is used. If the requested locale is not available, the collator will use a system-defined fallback locale. Use resolved-locale to test the results of locale fallback behavior.

Syntax


["collator",
    { "case-sensitive": boolean, "diacritic-sensitive": boolean, "locale": string }
]: collator

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.5.0	>= 4.2.0

format

Returns a formatted string for displaying mixed-format text in the text-field property. The input may contain a string literal or expression, including an 'image' expression. Strings may be followed by a style override object that supports the following properties:

"text-font": Overrides the font stack specified by the root layout property.
"text-color": Overrides the color specified by the root paint property.
"font-scale": Applies a scaling factor on text-size as specified by the root layout property.

Syntax


["format",
    input_1: string | image, options_1: { "font-scale": number, "text-font": array<string>, "text-color": color },
    ...,
    input_n: string | image, options_n: { "font-scale": number, "text-font": array<string>, "text-color": color }
]: formatted

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.48.0	>= 6.7.0	>= 4.6.0
text-font	>= 0.48.0	>= 6.7.0	>= 4.6.0
font-scale	>= 0.48.0	>= 6.7.0	>= 4.6.0
text-color	>= 1.3.0	>= 7.3.0	>= 4.10.0
image	>= 1.6.0	>= 8.6.0	>= 5.7.0

image

Returns a ResolvedImage for use in icon-image, *-pattern entries, and as a section in the 'format' expression.

A 'coalesce' expression containing image expressions will evaluate to the first listed image that is currently in the style. This validation process is synchronous and requires the image to have been added to the style before requesting it in the 'image' argument.

Every image name can be followed by an optional ImageOptions object, which will be used for vector images only.

To implement crossfading between two images within a symbol layer using the icon-image-cross-fade attribute, include a second image as the second argument in the 'image' expression.

Syntax


["image", "image_name", options: ImageOptions (can be omitted)]: ResolvedImage


["image",
    "image_name_1",
    options_1: ImageOptions (can be omitted),
    "image_name_2",
    options_2: ImageOptions (can be omitted)
]: ResolvedImage

Example: Use a fallback image

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 1.4.0	>= 8.6.0	>= 5.7.0

literal

Provides a literal array or object value.

Syntax


["literal", [...] (JSON array literal)]: array<T, N>


["literal", {...} (JSON object literal)]: object

Example: Display and style rich text labels

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

number

Asserts that the input value is a number. If multiple values are provided, each one is evaluated in order until a number is obtained. If none of the inputs are numbers, the expression is an error.

Syntax


["number", value]: number


["number", value, fallback: value, fallback: value, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

number-format

Converts the input number into a string representation using the providing formatting rules. If set, the locale argument specifies the locale to use, as a BCP 47 language tag. If set, the currency argument specifies an ISO 4217 code to use for currency-style formatting. If set, the unit argument specifies a simple ECMAScript unit to use for unit-style formatting. If set, the min-fraction-digits and max-fraction-digits arguments specify the minimum and maximum number of fractional digits to include.

Syntax


["number-format",
    input: number,
    options: { "locale": string, "currency": string, "min-fraction-digits": number, "max-fraction-digits": number }
]: string

Example: Display HTML clusters with custom properties

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.54.0	>= 8.4.0	>= 5.4.0

object

Asserts that the input value is an object. If multiple values are provided, each one is evaluated in order until an object is obtained. If none of the inputs are objects, the expression is an error.

Syntax


["object", value]: object


["object", value, fallback: value, fallback: value, ...]: object

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

string

Asserts that the input value is a string. If multiple values are provided, each one is evaluated in order until a string is obtained. If none of the inputs are strings, the expression is an error.

Syntax


["string", value]: string


["string", value, fallback: value, fallback: value, ...]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

to-boolean

Converts the input value to a boolean. The result is false when then input is an empty string, 0, false, null, or NaN; otherwise it is true.

Syntax


["to-boolean", value]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

to-color

Converts the input value to a color. If multiple values are provided, each one is evaluated in order until the first successful conversion is obtained. If none of the inputs can be converted, the expression is an error.

Syntax


["to-color", value, fallback: value, fallback: value, ...]: color

Example: Visualize population density

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

to-number

Converts the input value to a number, if possible. If the input is null or false, the result is 0. If the input is true, the result is 1. If the input is a string, it is converted to a number as specified by the "ToNumber Applied to the String Type" algorithm of the ECMAScript Language Specification. If multiple values are provided, each one is evaluated in order until the first successful conversion is obtained. If none of the inputs can be converted, the expression is an error.

Syntax


["to-number", value, fallback: value, fallback: value, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

to-string

Converts the input value to a string. If the input is null, the result is "". If the input is a boolean, the result is "true" or "false". If the input is a number, it is converted to a string as specified by the "NumberToString" algorithm of the ECMAScript Language Specification. If the input is a color, it is converted to a string of the form "rgba(r,g,b,a)", where r, g, and b are numerals ranging from 0 to 255, and a ranges from 0 to 1. If the input is an 'image' expression, 'to-string' returns the image name. Otherwise, the input is converted to a string in the format specified by the JSON.stringify function of the ECMAScript Language Specification.

Syntax


["to-string", value]: string

Example: Create a time slider

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

typeof

Returns a string describing the type of the given value.

Syntax


["typeof", value]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Feature data

accumulated

Returns the value of a cluster property accumulated so far. Can only be used in the clusterProperties option of a clustered GeoJSON source.

Syntax


["accumulated"]: value

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.53.0	>= 8.4.0	>= 5.5.0

feature-state

Retrieves a property value from the current feature's state. Returns null if the requested property is not present on the feature's state. A feature's state is not part of the GeoJSON or vector tile data, and must be set programmatically on each feature. Features are identified by their id attribute, which must be an integer or a string that can be cast to an integer. Note that ["feature-state"] can only be used with paint properties that support data-driven styling.

Syntax


["feature-state", string]: value

Example: Create a hover effect

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.46.0	>= 10.0.0	>= 10.0.0

geometry-type

Returns the feature's geometry type: Point, LineString or Polygon. Multi* feature types return the singular forms.

Syntax


["geometry-type"]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

id

Returns the feature's id, if it has one.

Syntax


["id"]: value

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

line-progress

Returns the progress along a gradient line. Can only be used in the line-gradient and line-z-offset properties.

Syntax


["line-progress"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.5.0	>= 4.6.0

properties

Returns the feature properties object. Note that in some cases, it may be more efficient to use ["get", "property_name"] directly.

Syntax


["properties"]: object

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Lookup

at

Retrieves an item from an array.

Syntax


["at", number, array]: ItemType

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

at-interpolated

Retrieves an item from an array. If the array contains numeric values and the provided index is non-integer, the expression returns an interpolated value between adjacent items.

Syntax


["at-interpolated", number, array]: ItemType

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.11.0	>= 11.12.0	>= 11.12.0

config

Retrieves the configuration value for the given option. Returns null if the requested option is missing.

Syntax


["config", string]: config


["config", string, string]: config

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.0.0	>= 11.0.0	>= 11.0.0

get

Retrieves a property value from the current feature's properties, or from another object if a second argument is provided. Returns null if the requested property is missing.

Syntax


["get", string]: value


["get", string, object]: value

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

has

Tests for the presence of an property value in the current feature's properties, or from another object if a second argument is provided.

Syntax


["has", string]: boolean


["has", string, object]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

in

Determines whether an item exists in an array or a substring exists in a string. In the specific case when the second and third arguments are string literals, you must wrap at least one of them in a literal expression to hint correct interpretation to the type system.

Syntax


["in",
    keyword: InputType (boolean, string, or number),
    input: InputType (array or string)
]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 1.6.0	>= 9.1.0	>= 5.8.0

index-of

Returns the first position at which an item can be found in an array or a substring can be found in a string, or -1 if the input cannot be found. Accepts an optional index from where to begin the search.

Syntax


["index-of",
    keyword: InputType (boolean, string, or number),
    input: InputType (array or string)
]: number


["index-of",
    keyword: InputType (boolean, string, or number),
    input: InputType (array or string),
    index: number
]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 1.10.0	>= 10.0.0	>= 10.0.0

length

Returns the length of an array or string.

Syntax


["length", string | array | value]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

measure-light

Returns a requested property of the light configuration based on the supplied options. Currently the only supported option is brightness which returns the global brightness value of the lights on a scale of 0 to 1, where 0 means total darkness and 1 means full brightness. This expression works only with 3D light, i.e. when lights root property is defined.

Syntax


["measure-light", string]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.0.0	>= 11.0.0	>= 11.0.0

slice

Returns an item from an array or a substring from a string from a specified start index, or between a start index and an end index if set. The return value is inclusive of the start index but not of the end index.

Syntax


["slice",
    input: InputType (array or string),
    index: number
]: OutputType (ItemType or string)


["slice",
    input: InputType (array or string),
    index: number,
    index: number
]: OutputType (ItemType or string)

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 1.10.0	>= 10.0.0	>= 10.0.0

split

Returns an array of substrings from a string, split by a delimiter parameter.

Syntax


["split", input_1: string, delimiter: string]: array<string>

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.14.0	>= 11.14.0	>= 11.14.0

worldview

Returns the current worldview being used.

Syntax


["worldview"]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.13.0	>= 11.13.0	>= 11.13.0

Decision

You can use decision expressions to add conditional logic to your styles. For example, the 'case' expression provides "if/then/else" logic, and 'match' allows you to map specific values of an input expression to different output expressions.

!

Logical negation. Returns true if the input is false, and false if the input is true.

Syntax


["!", boolean]: boolean

Example: Create and style clusters

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

!=

Returns true if the input values are not equal, false otherwise. The comparison is strictly typed: values of different runtime types are always considered unequal. Cases where the types are known to be different at parse time are considered invalid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


["!=", value, value]: boolean


["!=", value, value, collator]: boolean

Example: Display HTML clusters with custom properties

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

<

Returns true if the first input is strictly less than the second, false otherwise. The arguments are required to be either both strings or both numbers; if during evaluation they are not, expression evaluation produces an error. Cases where this constraint is known not to hold at parse time are considered in valid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


["<", value, value]: boolean


["<", value, value, collator]: boolean

Example: Display HTML clusters with custom properties

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

<=

Returns true if the first input is less than or equal to the second, false otherwise. The arguments are required to be either both strings or both numbers; if during evaluation they are not, expression evaluation produces an error. Cases where this constraint is known not to hold at parse time are considered in valid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


["<=", value, value]: boolean


["<=", value, value, collator]: boolean

Example: Animate 3D buildings based on ambient sounds

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

==

Returns true if the input values are equal, false otherwise. The comparison is strictly typed: values of different runtime types are always considered unequal. Cases where the types are known to be different at parse time are considered invalid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


["==", value, value]: boolean


["==", value, value, collator]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

>

Returns true if the first input is strictly greater than the second, false otherwise. The arguments are required to be either both strings or both numbers; if during evaluation they are not, expression evaluation produces an error. Cases where this constraint is known not to hold at parse time are considered in valid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


[">", value, value]: boolean


[">", value, value, collator]: boolean

Example: Animate 3D buildings based on ambient sounds

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

>=

Returns true if the first input is greater than or equal to the second, false otherwise. The arguments are required to be either both strings or both numbers; if during evaluation they are not, expression evaluation produces an error. Cases where this constraint is known not to hold at parse time are considered in valid and will produce a parse error. Accepts an optional collator argument to control locale-dependent string comparisons.

Syntax


[">=", value, value]: boolean


[">=", value, value, collator]: boolean

Example: Display HTML clusters with custom properties

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0
collator	>= 0.45.0	>= 6.5.0	>= 4.2.0

all

Returns true if all the inputs are true, false otherwise. The inputs are evaluated in order, and evaluation is short-circuiting: once an input expression evaluates to false, the result is false and no further input expressions are evaluated.

Syntax


["all", boolean, boolean]: boolean


["all", boolean, boolean, ...]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

any

Returns true if any of the inputs are true, false otherwise. The inputs are evaluated in order, and evaluation is short-circuiting: once an input expression evaluates to true, the result is true and no further input expressions are evaluated.

Syntax


["any", boolean, boolean]: boolean


["any", boolean, boolean, ...]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

case

Selects the first output whose corresponding test condition evaluates to true, or the fallback value otherwise.

Syntax


["case",
    condition: boolean, output: OutputType,
    condition: boolean, output: OutputType,
    ...,
    fallback: OutputType
]: OutputType

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

coalesce

Evaluates each expression in turn until the first valid value is obtained. Invalid values are null and 'image' expressions that are unavailable in the style. If all values are invalid, coalesce returns the first value listed.

Syntax


["coalesce", OutputType, OutputType, ...]: OutputType

Example: Use a fallback image

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

match

Selects the output for which the label value matches the input value, or the fallback value if no match is found. The input can be any expression (for example, ["get", "building_type"]). Each label must be unique, and must be either:

a single literal value; or
an array of literal values, the values of which must be all strings or all numbers (for example [100, 101] or ["c", "b"]).

The input matches if any of the values in the array matches using strict equality, similar to the "in" operator. If the input type does not match the type of the labels, the result will be the fallback value.

Syntax


["match",
    input: InputType (number or string),
    label: InputType | [InputType, InputType, ...], output: OutputType,
    label: InputType | [InputType, InputType, ...], output: OutputType,
    ...,
    fallback: OutputType
]: OutputType

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

within

Returns true if the evaluated feature is fully contained inside a boundary of the input geometry, false otherwise. The input value can be a valid GeoJSON of type Polygon, MultiPolygon, Feature, or FeatureCollection. Supported features for evaluation:

Point: Returns false if a point is on the boundary or falls outside the boundary.
LineString: Returns false if any part of a line falls outside the boundary, the line intersects the boundary, or a line's endpoint is on the boundary.

Syntax


["within", object]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 1.9.0	>= 9.1.0	>= 5.8.0

Ramps, scales, curves

interpolate

Produces continuous, smooth results by interpolating between pairs of input and output values ("stops"). The input may be any numeric expression (e.g., ["get", "population"]). Stop inputs must be numeric literals in strictly ascending order. The output type must be number, array<number>, or color.

Interpolation types:

["linear"]: Interpolates linearly between the pair of stops just less than and just greater than the input.
["exponential", base]: Interpolates exponentially between the stops just less than and just greater than the input. base controls the rate at which the output increases: higher values make the output increase more towards the high end of the range. With values close to 1 the output increases linearly.
["cubic-bezier", x1, y1, x2, y2]: Interpolates using the cubic bezier curve defined by the given control points.

Syntax


["interpolate",
    interpolation: ["linear"] | ["exponential", base] | ["cubic-bezier", x1, y1, x2, y2],
    input: number,
    stop_input_1: number, stop_output_1: OutputType,
    stop_input_n: number, stop_output_n: OutputType, ...
]: OutputType (number, array<number>, or Color)

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.42.0	>= 6.0.0	>= 4.0.0

interpolate-hcl

Produces continuous, smooth results by interpolating between pairs of input and output values ("stops"). Works like interpolate, but the output type must be color, and the interpolation is performed in the Hue-Chroma-Luminance color space.

Syntax


["interpolate-hcl",
    interpolation: ["linear"] | ["exponential", base] | ["cubic-bezier", x1, y1, x2, y2],
    input: number,
    stop_input_1: number, stop_output_1: Color,
    stop_input_n: number, stop_output_n: Color, ...
]: Color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.49.0	Not yet supported	Not yet supported

interpolate-lab

Syntax


["interpolate-lab",
    interpolation: ["linear"] | ["exponential", base] | ["cubic-bezier", x1, y1, x2, y2 ],
    input: number,
    stop_input_1: number, stop_output_1: Color,
    stop_input_n: number, stop_output_n: Color, ...
]: Color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.49.0	Not yet supported	Not yet supported

step

Produces discrete, stepped results by evaluating a piecewise-constant function defined by pairs of input and output values ("stops"). The input may be any numeric expression (e.g., ["get", "population"]). Stop inputs must be numeric literals in strictly ascending order. Returns the output value of the stop just less than the input, or the first output if the input is less than the first stop.

Syntax


["step",
    input: number,
    stop_output_0: OutputType,
    stop_input_1: number, stop_output_1: OutputType,
    stop_input_n: number, stop_output_n: OutputType, ...
]: OutputType

Example: Create and style clusters

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.42.0	>= 6.0.0	>= 4.0.0

Variable binding

let

Binds expressions to named variables, which can then be referenced in the result expression using ["var", "variable_name"].

Syntax


["let",
    string (alphanumeric literal), any, string (alphanumeric literal), any, ...,
    OutputType
]: OutputType

Example: Visualize population density

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

var

References variable bound using "let".

Syntax


["var", previously bound variable name]: the type of the bound expression

Example: Visualize population density

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

String

concat

Returns a string consisting of the concatenation of the inputs. Each input is converted to a string as if by to-string.

Syntax


["concat", value, value, ...]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

downcase

Returns the input string converted to lowercase. Follows the Unicode Default Case Conversion algorithm and the locale-insensitive case mappings in the Unicode Character Database.

Syntax


["downcase", string]: string

Example: Change the case of labels

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

is-supported-script

Returns true if the input string is expected to render legibly. Returns false if the input string contains sections that cannot be rendered without potential loss of meaning (e.g. Indic scripts that require complex text shaping, or right-to-left scripts if the the mapbox-gl-rtl-text plugin is not in use in Mapbox GL JS).

Syntax


["is-supported-script", string]: boolean

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.6.0	>= 4.1.0

resolved-locale

Returns the IETF language tag of the locale being used by the provided collator. This can be used to determine the default system locale, or to determine if a requested locale was successfully loaded.

Syntax


["resolved-locale", collator]: string

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.5.0	>= 4.2.0

upcase

Returns the input string converted to uppercase. Follows the Unicode Default Case Conversion algorithm and the locale-insensitive case mappings in the Unicode Character Database.

Syntax


["upcase", string]: string

Example: Change the case of labels

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Color

hsl

Creates a color value from hue (range 0-360), saturation and lightness components (range 0-100), and an alpha component of 1. If any component is out of range, the expression is an error.

Syntax


["hsl", number, number, number]: color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 2.12.1	>= 10.11.0	>= 10.11.0

hsla

Creates a color value from hue (range 0-360), saturation and lightness components (range 0-100), and an alpha component (range 0-1). If any component is out of range, the expression is an error.

Syntax


["hsla", number, number, number, number]: color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 2.12.1	>= 10.11.0	>= 10.11.0

rgb

Creates a color value from red, green, and blue components, which must range between 0 and 255, and an alpha component of 1. If any component is out of range, the expression is an error.

Syntax


["rgb", number, number, number]: color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

rgba

Creates a color value from red, green, blue components, which must range between 0 and 255, and an alpha component which must range between 0 and 1. If any component is out of range, the expression is an error.

Syntax


["rgba", number, number, number, number]: color

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

to-hsla

Returns a four-element array containing the input color's Hue, Saturation, Luminance and alpha components, in that order.

Syntax


["to-hsla", color]: array<number, 4>

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.9.0	>= 11.9.0	>= 11.9.0

to-rgba

Returns a four-element array containing the input color's red, green, blue, and alpha components, in that order.

Syntax


["to-rgba", color]: array<number, 4>

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Math

-

For two inputs, returns the result of subtracting the second input from the first. For a single input, returns the result of subtracting it from 0.

Syntax


["-", number, number]: number


["-", number]: number

Tutorial: Get started with Mapbox GL JS expressions: Calculate the age of each landmark

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

*

Returns the product of the inputs.

Syntax


["*", number, number, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

/

Returns the result of floating point division of the first input by the second.

Syntax


["/", number, number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

%

Returns the remainder after integer division of the first input by the second.

Syntax


["%", number, number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

^

Returns the result of raising the first input to the power specified by the second.

Syntax


["^", number, number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

+

Returns the sum of the inputs.

Syntax


["+", number, number, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

abs

Returns the absolute value of the input.

Syntax


["abs", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.0.0	>= 4.0.0

acos

Returns the arccosine of the input, in radians between −π/2 and π/2.

Syntax


["acos", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

asin

Returns the arcsine of the input, in radians between −π/2 and π/2.

Syntax


["asin", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

atan

Returns the arctangent of the input, in radians between −π/2 and π/2.

Syntax


["atan", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

ceil

Returns the smallest integer that is greater than or equal to the input.

Syntax


["ceil", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.0.0	>= 4.0.0

cos

Returns the cosine of the input, interpreted as radians.

Syntax


["cos", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

distance

Returns the shortest distance in meters between the evaluated feature and the input geometry. The input value can be a valid GeoJSON of type Point, MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon, Feature, or FeatureCollection. Distance values returned may vary in precision due to loss in precision from encoding geometries, particularly below zoom level 13.

Syntax


["distance", object]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.0.0	>= 9.2.0	>= 5.9.0

e

Returns the mathematical constant e.

Syntax


["e"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

floor

Returns the largest integer that is less than or equal to the input.

Syntax


["floor", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.0.0	>= 4.0.0

ln

Returns the natural logarithm of the input.

Syntax


["ln", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

ln2

Returns mathematical constant ln(2).

Syntax


["ln2"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

log10

Returns the base-ten logarithm of the input.

Syntax


["log10", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

log2

Returns the base-two logarithm of the input.

Syntax


["log2", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

max

Returns the maximum value of the inputs.

Syntax


["max", number, number, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

min

Returns the minimum value of the inputs.

Syntax


["min", number, number, ...]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

pi

Returns the mathematical constant pi.

Syntax


["pi"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

random

Returns a random value in the specified range (first two input numbers) based on a supplied seed (third input). The seed can be an expression or a constant number or string value.

Syntax


["random", number, number, value]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 3.0.0	>= 11.0.0	>= 11.0.0

round

Rounds the input to the nearest integer. Halfway values are rounded away from zero. For example, ["round", -1.5] evaluates to -2.

Syntax


["round", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.45.0	>= 6.0.0	>= 4.0.0

sin

Returns the sine of the input, interpreted as radians.

Syntax


["sin", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

sqrt

Returns the square root of the input.

Syntax


["sqrt", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.42.0	>= 6.0.0	>= 4.0.0

tan

Returns the tangent of the input, interpreted as radians.

Syntax


["tan", number]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Camera

distance-from-center

Returns the distance of a symbol instance from the center of the map. The distance is measured in pixels divided by the height of the map container. It measures 0 at the center, decreases towards the camera and increase away from the camera. For example, if the height of the map is 1000px, a value of -1 means 1000px away from the center towards the camera, and a value of 1 means a distance of 1000px away from the camera from the center. ["distance-from-center"] may only be used in the filter expression for a symbol layer.

Syntax


["distance-from-center"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 2.6.0	>= 10.9.0	>= 10.9.0

pitch

Returns the current pitch in degrees. ["pitch"] may only be used in the filter expression for a symbol layer.

Syntax


["pitch"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 2.6.0	>= 10.9.0	>= 10.9.0

zoom

Returns the current zoom level. Note that in style layout and paint properties, ["zoom"] may only appear as the input to a top-level "step" or "interpolate" expression.

Syntax


["zoom"]: number

Tutorial: Get started with Mapbox GL JS expressions: Add a zoom expression

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

Heatmap

heatmap-density

Returns the kernel density estimation of a pixel in a heatmap layer, which is a relative measure of how many data points are crowded around a particular pixel. Can only be used in the heatmap-color property.

Syntax


["heatmap-density"]: number

SDK Support	Mapbox GL JS	Android SDK	iOS SDK
basic functionality	>= 0.41.0	>= 6.0.0	>= 4.0.0

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Data expressions​

Camera expressions​

Composition​

Type system​

Expression reference

Types​

array​

Syntax

boolean​

Syntax

Related

collator​

Syntax

format​

Syntax

Related

image​

Syntax

Related

literal​

Syntax

Related

number​

Syntax

number-format​

Syntax

Related

object​

Syntax

string​

Syntax

to-boolean​

Syntax

to-color​

Syntax

Related

to-number​

Syntax

to-string​

Syntax

Related

typeof​

Syntax

Feature data​

accumulated​

Syntax

feature-state​

Syntax

Related

geometry-type​

Syntax

id​

Syntax

line-progress​

Syntax

properties​

Syntax

Lookup​

at​

Syntax

at-interpolated​

Syntax

config​

Syntax

get​

Syntax

Related

has​

Syntax

Related

in​

Syntax

Related

index-of​

Syntax

length​

Syntax

measure-light​

Syntax

slice​

Data expressions

Camera expressions

Composition

Type system

Types

array

boolean

collator

format

image

literal

number

number-format

object

string

to-boolean

to-color

to-number

to-string

typeof

Feature data

accumulated

feature-state

geometry-type

id

line-progress

properties

Lookup

at

at-interpolated

config

get

has

in

index-of

length

measure-light

slice

split

worldview

Decision

!

!=

<

<=

==

>

>=

all

any

case

coalesce

match

within

Ramps, scales, curves

interpolate

interpolate-hcl

interpolate-lab

step

Variable binding

let

var

String

concat

downcase

is-supported-script