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.