User Guide

The C-level API 379
JSBool JS_ValueToDouble()
Usage
JSBool JS_ValueToDouble(JSContext *cx, jsval v, double *dp);
Description
Method; extracts a function argument from a jsval structure, converts it to a double (if
possible), and passes the converted value back to the caller.
Arguments
JSContext *cx
, jsval v, double *dp
• The cx argument is the opaque JSContext pointer that passed to the JavaScript function.
• The v argument is the jsval structure from which the double is to be extracted.
• The dp argument is a pointer to an 8-byte double. This function stores the converted value
in
*dp.
Returns
A Boolean value: JS_TRUE indicates success; JS_FALSE indicates failure.
JSBool JS_ValueToBoolean()
Usage
JSBool JS_ValueToBoolean(JSContext *cx, jsval v, JSBool *bp);
Description
Method; extracts a function argument from a jsval structure, converts it to a Boolean value (if
possible), and passes the converted value back to the caller.
Arguments
JSContext *cx
, jsval v, JSBool *bp
• The cx argument is the opaque JSContext pointer that passes to the JavaScript function.
• The v argument is the jsval structure from which the Boolean value is to be extracted.
• The bp argument is a pointer to a JSBool Boolean value. This function stores the converted
value in
*bp.
Returns
A Boolean value: JS_TRUE indicates success; JS_FALSE indicates failure.