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Various utility functions, used by Leaflet internally.


Method Returns Description
extend( <Object> dest, <Object> src?.. ) Object Merges the properties of the src object (or multiple objects) into dest object and returns the latter. Has an L.extend shortcut.
bind( <Function> fn, <Object> obj ) Function Returns a function which executes function fn with the given scope obj (so that this keyword refers to obj inside the function code). Has an L.bind shortcut.
stamp( <Object> obj ) String Applies a unique key to the object and returns that key. Has an L.stamp shortcut.
requestAnimFrame( <Function> fn, <Object> context?, <Boolean> immediate?, <HTMLElement> element? ) Number Schedules fn to be executed when the browser repaints. When immediate is set, fn is called immediately if the browser doesn't have native support for requestAnimationFrame, otherwise it's delayed. Returns an id that can be used to cancel the request
cancelAnimFrame( <Number> id ) - Cancels a previous request to requestAnimFrame.
limitExecByInterval( <Function> fn, <Number> time, <Object> context? ) Function Returns a wrapper around the function fn that makes sure it's called not more often than a certain time interval time, but as fast as possible otherwise (for example, it is used for checking and requesting new tiles while dragging the map), optionally passing the scope (context) in which the function will be called.
falseFn() Function Returns a function which always returns false.
formatNum( <Number> num, <Number> digits ) Number Returns the number num rounded to digits decimals.
splitWords( <String> str ) String[] Trims and splits the string on whitespace and returns the array of parts.
setOptions( <Object> obj, <Object> options ) Object Merges the given properties to the options of the obj object, returning the resulting options. See Class options. Has an L.setOptions shortcut.
getParamString( <Object> obj ) String Converts an object into a parameter URL string, e.g. {a: "foo", b: "bar"} translates to '?a=foo&b=bar'.
template( <String> str, <Object> data ) String Simple templating facility, accepts a template string of the form 'Hello {a}, {b}' and a data object like {a: 'foo', b: 'bar'}, returns evaluated string ('Hello foo, bar'). You can also specify functions instead of strings for data values — they will be evaluated passing data as an argument.
isArray( <Object> obj ) Boolean Returns true if the given object is an array.
trim( <String> str ) String Trims the whitespace from both ends of the string and returns the result.


Property Type Description
emptyImageUrl String Data URI string containing a base64-encoded empty GIF image. Used as a hack to free memory from unused images on WebKit-powered mobile devices (by setting image src to this string).