Retrieve the number of elements in an array object.
Syntax
bool
JS_GetArrayLength(JSContext *cx, JS::Handle<JSObject*> obj,
uint32_t *lengthp);
| Name | Type | Description |
|---|---|---|
cx |
JSContext * |
The context in which to look up the array's length. Requires request. In a JS_THREADSAFE build, the caller must be in a request on this JSContext. |
obj |
JS::Handle<JSObject*> |
The object to examine. |
lengthp |
uint32_t * |
Out parameter. On success, *lengthp receives the length of the array. |
Description
JS_GetArrayLength gets the .length property of obj as though by calling JS_GetProperty and converts it to a 32-bit unsigned integer. If obj is an array (see JS_IsArrayObject), this is guaranteed to succeed, because the .length property of an array is always a number and can't be deleted or redefined.
On success, JS_GetArrayLength stores the length in *lengthp and returns true. On failure, it reports an error and returns false, and the value left in *lengthp is undefined.