Hide certain values in output from JSON.stringify()

Question

Is it possible to exclude certain fields from being included in the json string?

Here is some pseudo code

var x = {     x:0,     y:0,     divID:"xyz",     privateProperty1: 'foo',     privateProperty2: 'bar' } 

I want to exclude privateProperty1 and privateproperty2 from appearing in the json string

So I thought, I can use the stringify replacer function

function replacer(key,value) {     if (key=="privateProperty1") then retun "none";     else if (key=="privateProperty2") then retun "none";     else return value; } 

and in the stringify

var jsonString = json.stringify(x,replacer); 

But in the jsonString I still see it as

{...privateProperty1:value..., privateProperty2:value } 

I would like to the string without the privateproperties in them.

Answer 1

The Mozilla docs say to return undefined (instead of "none"):

http://jsfiddle.net/userdude/rZ5Px/

function replacer(key,value) {     if (key=="privateProperty1") return undefined;     else if (key=="privateProperty2") return undefined;     else return value; }  var x = {     x:0,     y:0,     divID:"xyz",     privateProperty1: 'foo',     privateProperty2: 'bar' };  alert(JSON.stringify(x, replacer)); 

Here is a duplication method, in case you decide to go that route (as per your comment).

http://jsfiddle.net/userdude/644sJ/

function omitKeys(obj, keys) {     var dup = {};     for (var key in obj) {         if (keys.indexOf(key) == -1) {             dup[key] = obj[key];         }     }     return dup; }  var x = {     x:0,     y:0,     divID:"xyz",     privateProperty1: 'foo',     privateProperty2: 'bar' };  alert(JSON.stringify(omitKeys(x, ['privateProperty1','privateProperty2']))); 

EDIT - I changed the function key in the bottom function to keep it from being confusing.