Jonas Schmedtmann

push() 末尾插入 返回数组长度

'use strict' //严格模式

const friends = ['Even', 'Hal', 'Peter'];
const newLength = friends.push('Flystone')
console.log(friends);//['Even', 'Hal', 'Peter'，'Flystone'];
console.log(newLength);//4

unshift() 首位插入

const friends = ['Even', 'Hal', 'Peter'];
friends.unshift('Flystone')
console.log(friends);//["Flystone","Even","Hal", "Peter"]

pop() 末尾删除 返回被删除的元素

const friends = ['Even', 'Hal', 'Peter'];
const popped = friends.pop();//删除最后一个
console.log(friends);//['Even', 'Hal']
console.log(popped)//Peter

shift() 首位删除 返回被删除的元素

const friends = ['Even', 'Hal', 'Peter'];
const shifted = friends.shift();
console.log(friends);//['Hal','Peter']
console.log(shifted);//Even

indexOf 查找数组中元素位置 数组中无此元素返回-1

const friends = ['Even', 'Hal', 'Peter'];
console.log(friends.indexOf('Hal'));//1
console.log(friends.indexOf('Flystone'));//-1

includes 查找数组中元素 有true 无false （ES6 严格相等===）

const friends = ['Even', 'Hal', 'Peter'];
console.log(friends.includes('Flystone'));//false
console.log(friends.includes('Even'));//true
friends.push('23')
console.log(friends.includes(23));//false