让代码简洁语义化

const obj = {
  a:'a',
  b:'b',
  c:'c'
}

const a = obj.a
const b = obj.b
const newName = obj.c

const {a,b,c:newName} = obj //对象解构赋值

//解构赋值语法从null，undefined结构会报错。如果不确定可以如下操作
const {a,b,c:newName} = obj || {}

const arr1 = [1,2,3]
const arr2 = [4,5,6]
const obj1 = {a:'a'}
const obj2 = {b:'b'}

const arr = arr1.concat(arr2)
const obj = Object.assign(obj1,obj2)

const arr = [...arr1,...arr2]
const arrs = [...new Set([...arr1,...arr2])] //去重
const obj = {...obj1,...obj2}

const name = '小明';
const score = 59;

let result = '';
if(score > 60){
  result = `${name}的考试成绩及格`; 
}else{
  result = `${name}的考试成绩不及格`; 
}

const result = `${name}${score > 60?'的考试成绩及格':'的考试成绩不及格'}`;

if(
    type == 1 ||
    type == 2 ||
    type == 3 ||
    type == 4 ||
){
   //...
}

const condition = [1,2,3,4];
if( condition.includes(type) ){
   //...
}

const fn1 = () =>{
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve(1);
    }, 300);
  });
}
const fn2 = () =>{
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve(2);
    }, 600);
  });
}
const fn = () =>{
   fn1().then(res1 =>{
      console.log(res1);// 1
      fn2().then(res2 =>{
        console.log(res2)
      })
   })
}

const fn = async () =>{
  const res1 = await fn1();
  const res2 = await fn2();
  console.log(res1);// 1
  console.log(res2);// 2
}