extend 扩展

extend.js

function extend(a, b) {
  var b = b || {};
  for (var prop in b) {
    if (Object.prototype.toString.call(b[prop]) === '[object Array]') {
      a[prop] = [];
      extend(a[prop], b[prop]);
    } 
    else if(Object.prototype.toString.call(b[prop]) === '[object Object]') {
      a[prop] = {};
      extend(a[prop], b[prop]);
    }
    else{
      a[prop] = b[prop];
    }
  }
  return a;
}

//
// test
//
var a = {};
var b = {
  index : 1,
  color: ['red', 'yellow', 'pink'],
  person:{
    name:'Bob',
    age:'26'
  }
}
console.log(a);
extend(a, b);
console.log(a);