数组去重

Set方法（es6新增）

    var arr = [1, 1, 4, 2, 2, 3, 3, 3, 6, 6, 6];
    arr = Array.from(new Set(arr));

indexOf

    var newArr = [];
    arr.forEach((item) => {
          newArr.indexOf(item) === -1 ? newArr.push(item) : "";
    });

includes方法

         var newArr = [];
    arr.forEach((item) => {
          newArr.includes(item) ? "" : newArr.push(item);
    });