var arr = [1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5];

 Array.prototype.forEach = Array.prototype.forEach || function(callback, thisArg) {

         if (!callback || typeof callback !== 'function') return;

         for (var i = 0, j = this.length; i < j; i++) {

             callback.call(thisArg, this[i], i, this);

         }

 }

 /*

    forEach方法实现数组去重

 */

 var newArr = [];

 arr.forEach(function(ele,index,arr){

     if(arr.indexOf(ele)===index){

         newArr.push(ele);

     }

 })

 console.log(newArr);