js对象深潜拷贝（从requirejs中抠出来的）

 var op = Object.prototype,
     ostring = op.toString,
     hasOwn = op.hasOwnProperty;

 function isFunction(it) {
     return ostring.call(it) === '[object Function]';
 };

 function isArray(it) {
     return ostring.call(it) === '[object Array]';
 };
 function hasProp(obj, prop) {
     return hasOwn.call(obj, prop);
 };
 function eachProp(obj, func) {
     var prop;
     for (prop in obj) {
         if (hasProp(obj, prop)) {
             if (func(obj[prop], prop)) {
                 break;
             }
         }
     }
 };
 /**
  * Simple function to mix in properties from source into target,
  * but only if target does not already have a property of the same name.
  *
  * @param {target} 目标对象
  * @param {source} 源对象
  * @param {force} 是否强制覆盖目标对象已有的属性
  * @param {deepStringMixin} 是否深拷贝递归操作
  *
  * @returns {target}
  */
 function mixin(target, source, force, deepStringMixin) {
     if (source) {
         eachProp(source, function (value, prop) {
             if (force || !hasProp(target, prop)) {
                 if (deepStringMixin && typeof value === 'object' && value &&
                     !isArray(value) && !isFunction(value) &&
                     !(value instanceof RegExp)) {

                     if (!target[prop]) {
                         target[prop] = {};
                     }
                     mixin(target[prop], value, force, deepStringMixin);
                 } else {
                     target[prop] = value;
                 }
             }
         });
     }
     return target;
 };

 调用：
 var obj = {
     name:'Tom',
     age:19,
     children:{
         name:'Jack',
         age:30
     }
 };
 var obj2 = mixin({},obj,false,true);
 obj.children.name='Marry';
 console.log(obj2);