Array.filter() 過濾不符合條件的值。

let a = [1,1,1,2,2,3,2,1,3];
let r = a.filter((item, i) => a.indexOf(item) == i);
console.log(r);

// 數(shù)組項為對象的去重
let a = [
    {index: 1},
    {index: 1},
    {index: 2},
    {index: 2},
    {index: 3},
    {index: 1},
];
let r = a.filter((item, i) => a.findIndex(j => j.index == item.index) == i);
console.log(r);