Question

I’m looking for a built-in method that combines two associative arrays or objects into one. Using webkit in Adobe Air if that makes a difference. But basically I have two objects or associative arrays if you will:

var obj1 = { prop1: "something", prop2 "anotherthing" };
var obj2 = { prop3: "somethingelse" };

and I want to do merge them and create an object that has all the combined keys and values of the above two objects:

var obj3 = obj1.merge( obj2 ); //something similar to array's concat maybe?

alert(obj3.prop1); //alerts "something"
alert(obj3.prop2); //allerts "anotherthing"
alert(obj3.prop3); //alerts "somethingelse"

Any built in function that does this or do I have to manually do it?

Answer 1

Like tryptych said, except that his example code (was dangerous and wrong, until he edited it). something a little more like the following would be better.

mylib = mylib || {};
//take objects a and b, and return a new merged object o;
mylib.merge = function(a, b) {

  var i, o = {};
  for(i in a) {
      if(a.hasOwnProperty(i)){
          o[i]=a[i];
      }
  }
  for(i in b) {
      if(b.hasOwnProperty(i)){
          o[i]=b[i];
      }
  }

  return o;

}
//take objects a and b, and modify object a to have b's properties
mylib.augment = function(a, b) {
  var i;
  for(i in b) {
      if(b.hasOwnProperty(i)){
          a[i]=b[i];
      }
  }
  return a;
}

edit re: ferocious. Deep copy is a different, and orthogonal function to this, but just for you, here’s my personal deep copy function

   function clone(o) {
    var t,i;
    if (o === undefined) {
        return undefined;
    }
    if (o === null) {
        return null;
    }
    if (o instanceof Function) {
        return o;
    }
    if (! (o instanceof Object)) {
        return o;
    } else {
        t = {};
        for (i in o) {
            /* jslint complains about this, it's correct in this case. I think. */
            t[i] = clone(o[i]);
        }
        return t;
    }
   }