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up vote 51 down vote favorite
3

jQuery.parseJSON and JSON.parse are two functions that perform the same task. If the jQuery library is already loaded, would using jQuery.parseJSON be better than using JSON.parse, in terms of performance?

If yes, why? If no, why not?

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I think JSON.parse isn't avaible at old browsers. In terms of speed they should be identical, JSON.parse should be little more faster (I think jQuery uses JSON.parse in newer browsers). – user1150525 Apr 28 '12 at 9:33

5 Answers 5

up vote 78 down vote accepted

Here is an extract from jQuery 1.9.1:

parseJSON: function( data ) {
    // Attempt to parse using the native JSON parser first
    if ( window.JSON && window.JSON.parse ) {
        return window.JSON.parse( data );
    }

    if ( data === null ) {
        return data;
    }

    if ( typeof data === "string" ) {

        // Make sure leading/trailing whitespace is removed (IE can't handle it)
        data = jQuery.trim( data );

        if ( data ) {
            // Make sure the incoming data is actual JSON
            // Logic borrowed from http://json.org/json2.js
            if ( rvalidchars.test( data.replace( rvalidescape, "@" )
                .replace( rvalidtokens, "]" )
                .replace( rvalidbraces, "")) ) {

                return ( new Function( "return " + data ) )();
            }
        }
    }

    jQuery.error( "Invalid JSON: " + data );
},

As you can see, jQuery will use the native JSON.parse method if it is available, and otherwise it will try to evaluate the data with new Function, which is kind of like eval.

So yes, you should definitely use jQuery.parseJSON.

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2  
Wow, great answers! Thanks everyone, I think yours is the most comprehensive answer. – Question Overflow Apr 28 '12 at 9:39
    
Depending on where your json comes from, there may be security issues with the fallback 'eval' method. – Steve Mayne Apr 28 '12 at 9:41
    
The rvalidchars.test stuff should catch invalid JSON; so this looks pretty safe. – Daniel Nov 28 '12 at 17:52
4  
Note that this is old, and an empty string will no longer return null. It will instead throw an error. – mlissner Apr 29 '13 at 18:51
up vote 11 down vote

According to jQuery

Where the browser provides a native implementation of JSON.parse, jQuery uses it to parse the string.

thus it means that jQuery provides a JSON parser if no native implementation exists on the browser. here's a comparison chart of browsers that have (and don't have) JSON functionality

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So I guessed right, without even knowing jQuery ;). – user1150525 Apr 28 '12 at 9:35
    
Thanks for the informative chart :) – Question Overflow Apr 28 '12 at 9:41
up vote 4 down vote

I don't know about performance, but it's definitely safer to use the jQuery method because some browsers like ie7 and lower might not have any JSON functionalities natively.
It's all about compatibility, just like you use jQuery's each method instead of the array's native forEach method for iteration.

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IE8 supports JSON. – RiZKiT Oct 27 '14 at 10:51
    
you're right. Thanks. updated the answer – gion_13 Jan 9 at 8:26
    
I always use JSON.parse(date) because of I never support IE8- and less characters than $.parseJSON() ^_^ For IE8- let's use like this <!--[if lt IE 8]><meta http-equiv="Refresh" content="0;url=/error-browser.html"><![endif]--> – xicooc Jan 16 at 3:35
up vote 6 down vote

JSON.parse() is natively available on some browsers, not on others, so it's safer to use a library. The JQuery implementation works well, as other respondents have noted. There's also Douglas Crockford's JSON library, which uses the native implementation if available.

The JSON library has the advantage that it has a method to turn a JavaScript object into a JSON string, which is missing from jQuery at the moment..

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up vote 1 down vote

This should improve this thread: http://caniuse.com/#feat=json

The JSON object has suppport in every single browser nowadays, so you should opt in for it instead of using jQuery's parseJSON, which I repeat, nowadays is unnecessary.

You can also search for this alias appearances at the repository, on github: https://github.com/jquery/jquery/search?utf8=%E2%9C%93&q=parseJSON

You should only use the jQuery's version if you're going to provide support for very, very, very old browsers.

Hope to help this old thread for people who have fallen here recently. Thumbs up if you agree. Best regards to all of you.

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