JavaScript之数组整理

数组：
一、增
1.创建数组
var color = ['red', 'blue'] //以下的color的初始值
2.添加元素到数组头部
var newColor = color.unshift('green') // ["green", "red", "blue"]
3.添加元素到数组尾部
var newColor = color.push('black') // ["red", "blue", "black"]

二、.删
1.删除头部元素
var newColor = color.shift() // ['blue']
2.删除尾部元素
var newColor = color.pop() //['red']
3,通过索引删除某个元素
var names = ["Bob", "Jack", "Alex"]
var newData = data.splice(1,2); // data : ["Bob"]; newData: ["Jack", "Alex"]

三、改
1.通过索引修改某个元素
var data = ["Jack", "Alex"]
var list = data .splice(1,1,'Lily'); // list: ["Jack", "Lily"]

四、.查
1.通过索引访问
let value = color[0] // 'red'
2.遍历
color.forEach(function(item, index, array){
console.log(item, index)
})
3.找出某元素在数组中的索引
var value = color.indexOf('blue'); // 1

五、其他
1.数组复制
var list = ["Jack", "Lily"]
let newList = list .slice(); //["Jack", "Lily"]
2.数组合并
var color1 = ['red', 'bule'];
var color2 = ['green', 'gray'];
var colorList = color1.concat(color2); // ["red", "bule", "green", "gray"]
3.用符号将数组连接成字符串
var colorList = ["red", "bule", "green", "gray"]
var arr = colorList.join(',') // "red,bule,green,gray"
4.数组转字符串
var colorString = colorList.toString() // "red,bule,green,gray"
5.数组排序
var colorList = ["red", "bule", "green", "gray"]
var val= colorList.sort(); // ["bule", "gray", "green", "red"]
6.倒序
var newVal = val.reverse(); // ["red", "green", "gray", "bule"]