数组去重

let arr1 = [1,2,3,4,2,3]
console.log([...new Set(arr1)])

数组合并

let arr1 = [1,2,3,4]
let arr2 = [5,6,7,8]
console.log([...arr1,...arr2])

数组合并去重

let arr1 = [1,2,3,4,2,3]
let arr2 = [5,6,7,8,5,6]
console.log([...new Set([...arr1, ...arr2])])

淘宝首页到底用了多少种标签（面试题）

new Set([...document.querySelectorAll('*')].map(v=>v.nodeName)).size

对象合并

let obj1 = {
     name: 'hello',
     age: 18
}
console.log({...obj1, name2: 'world', age2: '19'})

数组合并替换

let obj1 = {
     name: 'hello',
     age: 18
}
let obj2 = {
     name: 'world',
     age: 19
}
console.log({...obj1, ...obj2,name2: 'job', age2: '20'})