Question

Possible Duplicate:
What is the most efficient way to clone a JavaScript object?

I have an object like this:

User = {    
  name: "user",
  settings: {
    first: "1",
    second: "2"    
  }    
}

and a second one:

user1 = {
  name: "user1",
  settings: {
    second: "3"
  }
}

now I want to copy user1’s custom values into User, using:

    for(var key in user1){
        User[key] = user1[key];
    }

the result User will be:

User = {
  name: "user1",
  settings: {
    second: "3"
  }
}

User.settings has been entirely replace while I wanted only settings.second to be replaced.

How to achieve this, without knowing how much child object the main object have?

Answer 1

I’ve found that the best way to go is this:

http://andrewdupont.net/2009/08/28/deep-extending-objects-in-javascript/

Object.deepExtend = function(destination, source) {
  for (var property in source) {
    if (typeof source[property] === "object" &&
     source[property] !== null ) {
      destination[property] = destination[property] || {};
      arguments.callee(destination[property], source[property]);
    } else {
      destination[property] = source[property];
    }
  }
  return destination;
};


Object.extend(destination, source);

What about this?

    function clone(destination, source) {
        for (var property in source) {
            if (typeof source[property] === "object" && source[property] !== null && destination[property]) { 
                clone(destination[property], source[property]);
            } else {
                destination[property] = source[property];
            }
        }
    };