How To Safely Parse JSON

13 June 2007

Over the past few weeks I’ve witnessed several discussions about how to safely parse JSON in JavaScript. Most of these conversations hinge upon something like “because eval is simply not enough.” And they are right.

So how do you safely parse JSON in JavaScript? Luckily for us, most browsers today have native JSON support. For older browsers, Douglas Crockford created a polyfill called JSON-js.

Here’s a simple example of using the native or JSON-js JSON object:

var obj1 = { "foo": 42 };

// Create a JSON string from an object.
var str = JSON.stringify(obj1);

// Parse the JSON string into a new object.
var obj2 = JSON.parse(str);