double parse(String source, [double onError(String source)])

Parse source as an double literal and return its value.

Accepts an optional sign (+ or -) followed by either the characters "Infinity", the characters "NaN" or a floating-point representation. A floating-point representation is composed of a mantissa and an optional exponent part. The mantissa is either a decimal point (.) followed by a sequence of (decimal) digits, or a sequence of digits optionally followed by a decimal point and optionally more digits. The (optional) exponent part consists of the character "e" or "E", an optional sign, and one or more digits.

Leading and trailing whitespace is ignored.

If the source is not a valid double literal, the onError is called with the source as argument, and its return value is used instead. If no onError is provided, a FormatException is thrown instead.

The onError function is only invoked if source is a String with an invalid format. It is not invoked if the source is invalid for some other reason, for example by being null.

Examples of accepted strings:

"  3.14 \xA0"


external static double parse(String source,
                             [double onError(String source)]);