/**

  * 第一题

  * @param func

  * @param times

  * @param wait

  * @returns {repeatImpl}

  */

 function repeat (func, times, wait) {

     //不用匿名函数是为了方便调试

     function repeatImpl(){

         var handle,

             _arguments = arguments,

             i = 0;

         handle = setInterval(function(){

             i = i + 1;

             //到达指定次数取消定时器

             if(i === times){

                 clearInterval(handle);

                 return;

             }

             func.apply(null, _arguments);

         },wait);

     }

     return repeatImpl;

 }

 //测试用例

 var repeatFun = repeat(alert, 4, 3000);

 repeatFun("hellworld");

 /**

  * 第二题

  * @returns {string}

  */

 function stringconcat(){

     var result = [];

     stringconcat.merge.call(null, result, arguments);

     return result.join("+");

 }

 stringconcat.prefix = function(){

     var _arguments = [],

         _this = this;

     _this.merge.call(null, _arguments, arguments);

     return function(){

         var _args = _arguments.slice(0);

         _this.merge.call(null, _args, arguments);

         return _this.apply(null, _args);

     };

 };

 stringconcat.merge = function(array, arrayLike){

     var i = 0;

     for(i = 0; i < arrayLike.length; i++){

         array.push(arrayLike[i]);

     }

 }

 //测试用例

 var result1 = stringconcat("a", "b"); //result1 = "a+b"

 var result3 = stringconcat("c", "d"); //result1 = "a+b"

 var stringconcatWithPrefix = stringconcat.prefix("hellworld");

 var stringconcatWithPrefix1 = stringconcat.prefix("hellworld1");

 var result2 = stringconcatWithPrefix("a", "b"); //result2 = "hellworld+a+b"

 var result4 = stringconcatWithPrefix1("c", "d"); //result2 = "hellworld+a+b"

 alert(result1);

 alert(result2);

 alert(result3);

 alert(result4);