javascriptjqueryarraysobjecttypeof

Why does typeof array with objects return "object" and not "array"?

Why is an array of objects considered an object, and not an array? For example:

$.ajax({
    url: 'http://api.twitter.com/1/statuses/user_timeline.json',
    data: { screen_name: 'mick__romney'},
    dataType: 'jsonp',
    success: function(data) {
        console.dir(data); //Array[20]
        alert(typeof data); //Object
    }
});​

Fiddle

Solution

  • One of the weird behaviour and spec in Javascript is the typeof Array is Object.

    You can check if the variable is an array in couple of ways:

    var isArr = data instanceof Array;
var isArr = Array.isArray(data);

    But the most reliable way is:

    isArr = Object.prototype.toString.call(data) == '[object Array]';

    Since you tagged your question with jQuery, you can use jQuery isArray function:

    var isArr = $.isArray(data);