Check if jQuery method exists
<p>Is it possible? No matter how, in Javascript or jQuery.</p>

<p>For example: <code>$.isFunction($.isFunction());</code></p>

<p>Upd: But how to check method of a jQuery plugin? Sometimes it not ready at the moment of it call and generates error. Example: <code>$.isFunction($().jqGrid.format)</code></p>
