Js 배열 연산의 기본 방법을 설명합니다.

var newArr = [1,2,3];

newArr  instanceof Array;   // true
Array.isArray(newArr) ;   // true

//Array.isArray(newArr) 只支持ie9+,firefox 4+,safari 5+,opera 10.5+和chrome

var newArr = new Array(); // 创建数组
var newArr = new Array(3);  // 创建数组并指定长度
var newArr = new Array(1,2,[3,4]);  //创建数组并赋值

var newArr = new Array(); // 创建数组
var newArr = new Array(3);  // 创建数组并指定长度
var newArr = new Array(1,2,[3,4newArr.push('A');  //6
newArr;  // [1,2,3,4,5,'A']

newArr.unshift('B'); //7
newArr; // ['B',1,2,3,4,5,'A']

newArr.splice(2,0,'C'); // []
newArr; //["B", 1, "C", 2, 3, 4, 5, "A"]]);  //创建数组并赋值

var newArr = [1,2,3,4,5];

newArr.pop();  //5
newArr;  // [1,2,3,4]

newArr.shift(); //1
newArr;  // [2,3,4]

newArr.splice(1,2); //[3,4]
newArr;  //[2]

var newArr = ['A','B','C','D','E'];

newArr.slice(2); //["C", "D", "E"]
newArr.slice(1,4); //["B", "C", "D"]

newArr.concat('M');  //["A", "B", "C", "D", "E", "M"]

var newArr = ['A','B','C','D','E'];

newArr.slice(0); //["A", "B", "C", "D", "E"]
newArr.concat();  //["A", "B", "C", "D", "E"]

var newArr = ['A','C','B','D','M'];

newArr.reverse();  //["M", "D", "B", "C", "A"]
newArr.sort();  //"A", "B", "C", "D", "M"]

var  newArr = [1,2,3];

newArr.join(',');  // "1,2,3"
newArr.toString();  //"1,2,3"
newArr.toLocaleString (); //"1,2,3"
newArr.valueOf();  //[1,2,3]

//toLocaleString 、toString 、valueOf：可以看作是join的特殊用法，不常用

var newArr = [1,2,3,4,5,4,3,2,3,4];

newArr.indexOf(3);  // 第一次出现元素3的位置 :2
newArr.indexOf(3,4); //从位置3开始查找第一次出现元素4的位置：6

newArr.lastIndexOf(3); //最后一次出现元素3的位置：8
newArr.lastIndexOf(2,4); //从位置4开始查找最后一次出现元素2的位置：1


var person={name:"lili"},
    person1=[{name:"lili"}],
    person2=[person];

person1.indexOf(person);//返回-1 必须严格相等,不仅仅是值相等
person2.indexOf(person);//返回0


// indexOf()从前往后查找，找不到为-1
// lastIndexOf()从后往前查找，找不到为-1