利用indexOf消除数组中重复的元素

let arr=[1,5,8,69,4,11,11,69,5,1,8,56,85,56,56];

let arr2=[];

for(let i=0; i < arr.length; i++){

    if(arr2.indexOf(arr[i])<0){

        arr2.push(arr[i]);

    }

}

console.log(arr2);