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How can I programmatically detect if an object is a jQuery object? For example:
// 1. declare some variables
var vars = [1, 'hello', ['bye', 3], $(body), { say: 'hi' }];
// 2. ??? : implement function that tests whether its parameter is a jQuery object
function isjQuery(arg) { /* ??? */ }
// 3. profit
var test = $.map(vars, isjQuery); /* expected [ false, false, false, true, false ] */
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$(this) is a jQuery wrapper around that element that enables usage of jQuery methods. jQuery calls the callback using apply() to bind this . Calling jQuery a second time (which is a mistake) on the result of $(this) returns an new jQuery object based on the same selector as the first one.
The jQuery Object: The Wrapped Set: Selectors return a jQuery object known as the "wrapped set," which is an array-like structure that contains all the selected DOM elements. You can iterate over the wrapped set like an array or access individual elements via the indexer ($(sel)[0] for example).
The easiest API-documented way is to test for the .jquery property:
function isjQuery(arg) {
return !!arg.jquery;
}
However, if you want to be sure it's a jQuery object and not some other object with a fake .jquery property, the other answers suggesting instanceof jQuery and testing the constructor work too.
(The .jquery property is formally a string indicating the jQuery version, but the API example uses it to test whether an object is a jQuery object.)
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