var arr=[2,8,5,6,7,8,1,5,4,7,85,1,5];
var arr2=[1,5,8,4,2,9,3,5,2,1];
Array.prototype.quchong=function(){
var result=[];
for (var i = 0; i ++) {
if (result.indexOf(this[i])<0) {
result.push(this[i]);
}
}
return result;
}
console.log(arr.quchong());