js 数组去重复、内置方法

var arr=[1,2,1,5,2,3,5,1,6,9];
function deRepeat(){
  var newArray=[];
  var obj={};
  var index=0;
  var len=arr.length;
for(var i=0;i<len;i++){
    if(obj[arr[i]]==undefined){//不存在
       obj[arr[i]]=1;
       newArray[index++]=arr[i];
    }else if(obj[arr[i]]==1)
      continue;
    }
     return newArray;
  }

alert(deRepeat(arr));

var arr=[1,2,1,5,2,3,5,1,6,9];
     for(var i=0,obj={},newArray=[],len=arr.length;i<len;i++){
          if(!obj[arr[i]]){
                  obj[arr[i]]=1;
                   newArray.push(arr[i])
             }
        }
        alert(newArray)
 

String.prototype.repeatify = String.prototype.repeatify || function(times) {
 
var str = ‘‘;
 
for (var i = 0; i < times; i++) {
 
str += this;
 
}
 
return str;
 
};
console.log(‘hello‘.repeatify(3));

//hellohellohello