simple javascript extend function

extend.js

  var extend = function () {
    if (arguments.length == 0)
      return {};

    if (arguments.length == 1)
      return arguments[0];

    var nResult = {};

    for (var i = 0; i < arguments.length; i++) {
      var source = arguments[i];
      for (var prop in source) {
        if (typeof source[prop] === "object" && source[prop] !== null) {
          nResult[prop] = extend(nResult[prop] || {}, source[prop]);
        } else {
          nResult[prop] = source[prop];
        }
      }
    }

    return nResult;
  };
  
  var obj1 = { prop1: "abc", prop2: { subProp1: 123, subProp2:456 } };
  var obj2 = { prop2: { subProp1: 321, subProp3: 789 }, prop3: 'def' };
  var obj3 = { prop4: 'hij'};

  var nResult = extend(obj1, obj2, obj3);
  console.log(nResult);
  
/*
  { prop1: 'abc',  prop2: { subProp1: 321, subProp2: 456, subProp3: 789 },  prop3: 'def',  prop4: 'hij' }
*/