JS 快速找到数组索引

var array =[7,62,34,1,88,576,984,32,'...'];
function findIndex(num,arr){
var s='';
for(var i in arr){
if(arr[i]==num) s+=arr[i]+' 的索引为：'+i+'  ';
}
if(s=='') s='数字'+num+'不存在！';
return s ;
} 

//测试
array[8888]=888;
//array['re']=555;
var result=findIndex(34,array);
document.write(result);