Checking types in JavaScript can be a little tricky, especially with browser (and language) quirks. In light of this recent article I’ve made a small helper function using the recommended method:

The Code:

function type(o){
    return !!o && Object.prototype.toString.call(o).match(/(\w+)\]/)[1];
}

Usage:

type(101);          // returns 'Number'
type('hello');      // returns 'String'
type({});           // returns 'Object'
type([]);           // returns 'Array'
type(function(){}); // returns 'Function'
type(new Date());   // returns 'Date'
type(document);     // returns 'HTMLDocument'
 
// For example, to test for an Array:
if( type([1,2,3,4,5]) === 'Array' ) {
    doStuff();
}

This new function makes a few improvements on the shameful typeof operator. For one thing you can now successfully test for an array!

Here’s an alternative implementation:

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