Obsolete since JSAPI 38
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Converts a JavaScript value to a value of a specific JavaScript type.
Syntax
bool JS_ConvertValue(JSContext *cx, JS::HandleValue v, JSType type, JS::MutableHandleValue vp);
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 |
JS::HandleValue |
The value to convert. |
type |
JSType |
The type to which the value is to be converted. type must be one of JSTYPE_VOID , JSTYPE_OBJECT , JSTYPE_FUNCTION , JSTYPE_STRING , JSTYPE_NUMBER , or JSTYPE_BOOLEAN . Otherwise JS_ConvertValue reports an error. |
vp |
JS::MutableHandleValue |
Out parameter. On success, *vp receives the converted value. |
Description
JS_ConvertValue
converts a JavaScript value, v
, to the specified type
. On success, the converted value is stored in *vp
. Typically users of this function set vp
to point to v
, so that if conversion is successful, v
now contains the converted value.
JS_ConvertValue
calls other, type-specific conversion routines based on the type
argument.
- Converting any value to
JSTYPE_VOID
always succeeds. The result isundefined
value. - Converting to
JSTYPE_OBJECT
works exactly likeJS::ToObject
ifv.isNullOrUndefined()
isfalse
, otherwise the result isnullptr
. - Converting to
JSTYPE_FUNCTION
works likeJS_ValueToFunction
, but better: the result is a function object that has not been stripped of its lexical scope. It is safe to call the result (e.g. usingJS_CallFunctionValue
). - Converting to
JSTYPE_STRING
works likeJS::ToString
. - Converting to
JSTYPE_NUMBER
works exactly likeJS::ToNumber
. - Converting to
JSTYPE_BOOLEAN
works exactly likeJS::ToBoolean
.
On success, JS_ConvertValue
stores the converted value in *vp
and returns true
. On error or exception, it returns false
, and the value left in *vp
is undefined.