ES8知识点

1：Object.value获取对象的value值

const obj = {
    name: 'tyy',
    age: 18
}
console.log(Object.keys(obj));
console.log(Object.values(obj));

 

 2：Object.entries 获取对应键值对 作用方便遍历

const obj = {
    name: 'tyy',
    age: 18
}
const items = Object.entries(obj)
console.log(Object.entries(obj));
//方便遍历
items.forEach(item => {
    console.log(item[0], item[1]);
})
console.log(Object.entries(['aaa', 'bbb', 'ccc']));
console.log(Object.entries('abc'));

 

 3: String 的padEnd padStart 隐藏开始和隐藏结束

//基本使用
const s = "Hello World"
const s2 = s.padStart(15, '#').padEnd(20, '$')
console.log(s2);
//应用场景 隐藏身份证号码
const card = "5117283727987177897"
const lastfourcrad = card.slice(-4)
const finnalcard = lastfourcrad.padStart(card.length, "*")
console.log(finnalcard);

 

 4：Trailing-Commas:参数后面可以加逗号

function foo(x, y, z, ) {
    console.log(x, y, z, );
}
foo(1, 2, 3, )

5：Object.getOwnPropertyDescriptors

const obj = {
    name: 'tyy',
    age: 20
}
console.log(Object.getOwnPropertyDescriptors(obj));