JavaScript的数组方法（javascript中的数组方法）

const numbers=[43,45,56,33,44,1,7];

const numbers2=new Array(22,40,32,76,99);

const fruit=["apple","banana","orange","pear"]

const mixed=[22,"helllo",true,undefined,null,{a:1,b:2},new Date()];

let val;

//获取长度

val=numbers.length; //(7) [43, 45, 56, 33, 44, 1, 7]

//检查是不是数组

val=Array.isArray(numbers); //true

//获取数组单个元素

val=numbers[3]; //33

//更改某个元素值

numbers[2]=100; //56变100

//查找元素下标位置

val=numbers.indexOf(44); //4

//添加和删除

numbers.push(250); //从后面加：(8) [43, 45, 100, 33, 44, 1, 7, 250]

numbers.unshift(120); //从前面加：(9) [120, 43, 45, 100, 33, 44, 1, 7, 250]

numbers.pop(); //从后面删除：(8) [120,43, 45, 100, 33, 44, 1, 7]

numbers.shift(); //从前面删除：(7) [43, 45, 100, 33, 44, 1, 7]

//删掉多个

numbers.splice(1,3);//(4) [43, 44, 1, 7]

//反转

numbers.reverse();//反转(4) [7, 1, 44, 43]

//数组拼接

val=numbers.concat(numbers2); //(9)[7, 1, 44, 43, 22, 40, 32, 76, 99]

//排序

val=fruit.sort(); //(4) ["apple", "banana", "orange", "pear"]

val=numbers.sort(); //(4) [1, 43, 44, 7]

val=numbers.sort(function(x,y){

return x-y;

}); //(4) [1, 7, 43, 44]

console.log(numbers);

console.log(val);