JS_ValueToNumber

Convert any JavaScript value to a floating-point number of type jsdouble.

Syntax

JSBool JS_ValueToNumber(JSContext *cx, jsval v, jsdouble *dp);

Name	Type	Description
`cx`	`JSContext *`	The context in which to perform the conversion. Requires request. (In a `JS_THREADSAFE` build, the caller must be in a request on this `JSContext`.)
`v`	`jsval`	The value to convert.
`dp`	`jsdouble *`	Out parameter. On success, `*dp` receives the converted floating-point value.

Description

JS_ValueToNumber converts a JavaScript value to a number. It implements the ToNumber operator described in ECMA 262-3 §9.3 .

If v is already a number, conversion succeeds.
If v is undefined, null, false, or true, conversion succeeds, and the result is NaN, 0, 0, or 1 respectively.
If v is a string, conversion proceeds as specified in ECMA 262-3 §9.3.1 . JS_ValueToNumber always succeeds in this case, returning JS_TRUE. If the string is not a numeric string, the jsdouble dp out parameter is set to NaN.
If v is an object, conversion is successful if the object's JSClass.convert callback returns a primitive value that can be converted.

On success, JS_ValueToNumber stores the converted value in *dp and returns JS_TRUE. On error or exception, it returns JS_FALSE, and the value left in *dp is undefined.

JS_ValueToNumber

Table of contents

Syntax

Description

See Also

Files (0)