Generating JSON of a JS-Object with only some attributes in JSON

I'm generating JSON from a javascr开发者_开发百科ipt object. But I do not need all attributes from the object in the JSON. Is there a way (or a library) to do this? Till now, I overrided the toJSON function and return a new Object with reduced attributes, but its a nasty workaround, isn't it?

JSON.stringify accepts a second parameter, a "replacer" function, that you may be able to use to exclude certain properties.

var exclude = { 'akey': true };

var obj = { 'akey': 2, 'anotherkey': 3 };

JSON.stringify(obj, function (key, value) {
    if(exclude[key]) return undefined;
    return value;
});

=> "{'anotherkey':3}"

Funny I just wrote some code to do this (with objects) which you can then serialize the target.

// sorta like $.extend but limits to updating existing properties
// from a template. takes any number of objects to merge.
function mergeObjects(template) {
    var obj={};
    if (arguments) {
        for (var i = 0; i < arguments.length; i++) {
            newObj = arguments[i];
            for (var prop in template) {
                if (newObj.hasOwnProperty(prop)) {
                    obj[prop] = newObj[prop];
                }
            }
        }
    }
    return obj;
}

The way to use this function is with a template object that has the properties you need, e.g.

var template = {
  firstname: '',
  lastname: ''
}

var someObject = {
  firstname: "bryce",
  lastname: "nesbitt",
  title: "ubergeek"
}

var filteredObject = mergeObjects(template,someObject);

-->

   filteredObject: {
      firstname: "bryce",
      lastname: "nesbitt",
    }

http://jsfiddle.net/AARMW/