How can I merge 2 javascript objects, populating the properties in one if they don't exist in the other?

Question

If I have a javascript object/assoc. array defined like this:

function somefunction(options) {

    var defaults = {
        prop1: \'foo\',
        prop2: \'bar         


        

Answer 1

Using Google Closure Library it can be done like that:

goog.require('goog.object');
function somefunction(options) {
  var defaults = {
    prop1: 'foo',
    prop2: 'bar'
  };
  goog.object.extend(defaults, options);
  // if the property is defined in options it will overwrite value.
}