{"json_modified": "2016-03-28T08:17:06.856176", "uuid": "eee49257-56ca-4004-aa8e-899b32a4905f", "title": "JS_GetFunctionArity", "url": "/en-US/docs/Mozilla/Projects/SpiderMonkey/JSAPI_reference/JS_GetFunctionArity", "tags": ["SpiderMonkey", "JSAPI Reference"], "translations": [], "modified": "2015-01-05T03:42:37", "label": "JS_GetFunctionArity", "localization_tags": [], "locale": "en-US", "id": 19151, "last_edit": "2015-01-05T03:42:28", "summary": "<code>JS_GetFunctionArity</code> returns the number of formal parameters of a function, <code>fun</code>. This is the same as the function object's <code>arity</code> property, if that property has not been overwritten. Specifically, if <code>fun</code> is a native function, the result is the value that was passed to the <code>nargs</code> parameter of <a href=\"/en-US/docs/Mozilla/Projects/SpiderMonkey/JSAPI_reference/JS_DefineFunction\" title=\"Create a native function and assign it as a property to a specified JS object.\"><code>JS_DefineFunction</code></a>. Otherwise <code>fun</code> is implemented in JavaScript, and the result is the number of identifiers in its formal parameter list (see <a href=\"https://bclary.com/2004/11/07/#a-13\">ECMA 262-3 \u00a713</a>).", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "Description", "title": "Description"}, {"id": "See_Also", "title": "See Also"}], "slug": "Mozilla/Projects/SpiderMonkey/JSAPI_reference/JS_GetFunctionArity", "review_tags": []}