Alternatives to JavaScript eval() for parsing JSON

Damien picture Damien · Jun 3, 2009 · Viewed 45.2k times · Source

Quick Question. Eval in JavaScript is unsafe is it not? I have a JSON object as a string and I need to turn it into an actual object so I can obtain the data:

function PopulateSeriesFields(result) 
{
    data = eval('(' + result + ')');
    var myFakeExample = data.exampleType
}

If it helps I am using the $.ajax method from jQuery.

Thanks

Answer

Rene Saarsoo picture Rene Saarsoo · Jun 3, 2009

Well, safe or not, when you are using jQuery, you're better to use the $.getJSON() method, not $.ajax():

$.getJSON(url, function(data){
    alert(data.exampleType);
});

eval() is usually considered safe for JSON parsing when you are only communicating with your own server and especially when you use a good JSON library on server side that guarantees that generated JSON will not contain anything nasty.

Even Douglas Crockford, the author of JSON, said that you shouldn't use eval() anywhere in your code, except for parsing JSON. See the corresponding section in his book JavaScript: The Good Parts