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I have seen references to some browsers natively supporting JSON parsing/serialization of objects safely and efficiently via the window.JSON Object, but details are hard to come by. Can anyone point in the right direction? What are the methods this Object exposes? What browsers is it supported under?

See When can I use JSON parsing? for info on browsers with native support for the JSON object . – outis Dec 26, 2011 at 9:38

All modern browsers support native JSON encoding/decoding (Internet Explorer 8+, Firefox 3.1+, Safari 4+, and Chrome 3+). Basically, JSON.parse(str) will parse the JSON string in str and return an object, and JSON.stringify(obj) will return the JSON representation of the object obj .

More details on the MDN article .

I know the support is not widespread, but using this method should be a lot faster and safer than eval()ing a string, so I want to use it where it's available. Any idea on support from other browsers? – levik May 21, 2009 at 3:53 Oh, and on a side note, NEVER eval() JSON strings. Instead, use one of the many JSON parsing libraries available. – Sasha Chedygov May 21, 2009 at 4:08 For reference, when you say "NEVER eval() ..." and then mention that json2 is the popularly supported library, it's worth noting that it does use eval, but it attempts to validate the string using regex first. This is faster than validating and parsing the string, though there are parsers that don't validate with comparable performance. json2.js is still probably the best choice, if only for its pervasiveness. – TheXenocide Nov 21, 2011 at 16:40 @TheXenocide: Good point, but its author probably spent a good chunk of time on that validation code, so I say never eval() JSON strings because you will be reinventing the wheel and you will likely get it wrong. – Sasha Chedygov Nov 28, 2011 at 20:00 // Make sure leading/trailing whitespace is removed (IE can't handle it) data = jQuery.trim( data ); // Attempt to parse using the native JSON parser first if ( window.JSON && window.JSON.parse ) { return window.JSON.parse( 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 ); rvalidescape = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, rvalidtokens = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, rvalidbraces = /(?:^|:|,)(?:\s*\[)+/g,

The advantage of using json2.js is that it will only install a parser if the browser does not already have one. You can maintain compatibility with older browsers, but use the native JSON parser (which is more secure and faster) if it is available.

Browsers with Native JSON:

Firefox 3.1+

Safari 4.0.3+

Opera 10.5+

Internally it checks if browser supports .JSON.parse, and (if available) calls native window.JSON.parse.

If not, does parse itself.

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