In actual projects, it is inevitable to encounter duplication of elements in the array. The following will introduce several methods for deduplication of ES6 arrays:
1. Use Set to deduplicate
const arr = ['张三','张三','三张三']
let set = new Set(arr); // set 自带去重
// Set { '张三', '三张三' }
console.log(set);
console.error(Array.from(set)); // [ '张三', '三张三' ]
2. Use reduce to deduplicate
let person = [
{id: 0, name: "小明"},
{id: 1, name: "小张"},
{id: 2, name: "小李"},
{id: 3, name: "小孙"},
{id: 1, name: "小周"},
{id: 2, name: "小陈"},
];
let obj = {};
let peon = person.reduce((cur,next) => {
obj[next.id] ? "" : obj[next.id] = true && cur.push(next);
return cur;
},[]) //设置cur默认类型为数组,并且初始值为空的数组
console.log(peon);
// (4) [{…}, {…}, {…}, {…}]0: {id: 0, name: "小明"}1: {id: 1, name: "小张"}2: {id: 2, name: "小李"}3: {id: 3, name: "小孙"}length: 4__proto__: Array(0)
3. Use reduceRight to deduplicate and reverse the order of the array
let hash = {};
let config = [{
name: 2,
state: true,
output: 'Y',
}, {
name: 3,
state: true,
output: 'A',
}, {
name: 5,
state: true,
output: 'S',
}, {
name: 7,
state: true,
output: 'B',
}];
config = [...config, {
name: 3,
state: false,
output: 'A',
}]
const newArr = config.reduceRight((item, next) => {
hash[next.name] ? '' : hash[next.name] = true && item.push(next);
return item
}, []);
console.log(JSON.stringify(newArr));
// [{"name":3,"state":false,"output":"A"},{"name":7,"state":true,"output":"B"},{"name":5,"state":true,"output":"S"},{"name":2,"state":true,"output":"Y"}]
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