JS Object Merge

extend.js

function extend(){
  var output = {}, 
    args = arguments,
    l = args.length;

  for ( var i = 0; i < l; i++ )       
    for ( var key in args[i] )
      if ( args[i].hasOwnProperty(key) )
        output[key] = args[i][key];
  return output;
}

usage.js

// Default object
var defaults = {
  asdf: 1,
  jkl: 200
}

// opts object: extends and overwrites defaults
var opts = {
  asdf: 2,
  foo: 10
}

var options = extend(defaults, opts)

/* 
returns: {
  asdf: 2,
  jkl: 200,
  foo: 10
}
*/