数组去重

function unique(arr) {
    var arr1 = [];  
    for (var i = 0, len = arr.length; i < len; i++) {
        console.log(i)
        if (arr1.indexOf(arr[i]) === -1) {
            arr1.push(arr[i]);
        }
    }
    return arr1;
}

var arr=[11,54,34,1,56,67,56]
var newArr=Array.from(new Set(arr))
console.log(newArr)//[11,54,34,1,56,67]

var newArr1=[...new Set(arr)]
console.log(newArr1)//[11,54,34,1,56,67]

var newArr2=(...new Set(arr))
console.log(newArr2)//[11,54,34,1,56,67]