js数组中判断是否有重复项

let s = ary.join(",")+",";
for(let i=0;i<ary.length;i++) {
    if(s.replace(ary[i]+",","").indexOf(ary[i]+",")>-1) {
        alert("数组中有重复元素：" + ary[i]);
        break;
    }
}        

let  ary = new Array("111","22","33","111");
let nary=ary.slice().sort();
for(let i=0;i<ary.length;i++){
    if (nary[i]==nary[i+1]){
        alert("数组重复内容："+nary[i]);
    }
}    

function isRepeat(arr){
    let  hash = {};
    for(let i in arr) {
        if(hash[arr[i]]) {
            return true;
　　     }
        hash[arr[i]] = true;
    }
    return false;
}