js數(shù)組容器中包含的屬性和方法概述

1、.length----獲取數(shù)組長(zhǎng)度；

var arr = [1,2,3,4,5];
console.log(arr.length)  //5

2、shift()----刪除原數(shù)組第一項(xiàng)，并返回刪除元素的值；如果數(shù)組為空則返回undefined，直接在元數(shù)組上修改；

var arr= [1,2,3,4,5];
var result = arr.shift(); 
console.log(arr)   //[2,3,4,5]
console.log(result)   //1

3、unshift()----將參數(shù)添加到原數(shù)組開(kāi)頭，并返回?cái)?shù)組的長(zhǎng)度，直接在元數(shù)組上修改；

arr = [1,2,3,4,5];
result = arr.unshift(-2,-1);
console.log(arr)   //[-2,-1,1,2,3,4,5]
console.log(result)   //7

4、pop()----刪除原數(shù)組最后一項(xiàng)，并返回刪除元素的值；如果數(shù)組為空則返回undefined，直接在元數(shù)組上修改；

arr= [1,2,3,4,5];
result = arr.pop(); 
console.log(arr)   //[1,2,3,4] 
console.log(result)   //5

5、push()----將參數(shù)添加到原數(shù)組末尾，并返回?cái)?shù)組的長(zhǎng)度，直接在元數(shù)組上修改；

arr = [1,2,3,4,5];
result = arr.push(6,7);
console.log(arr)    //[1,2,3,4,5,6,7]
console.log(result)   //7

6、concat()----數(shù)組合并，返回一個(gè)新數(shù)組，不影響原數(shù)組；

arr = [1,2,3,4,5];
result = arr.concat(6,7);
console.log(arr);   //[1,2,3,4,5] 
console.log(result);  //[1,2,3,4,5,6,7]

7、sort()----將數(shù)組從小到大排序，直接在原數(shù)組上修改；

arr = [4,5,2,3,1];
result = arr.sort();
    console.log(arr);   //[1, 2, 3, 4, 5]
console.log(result)   //[1, 2, 3, 4, 5]

8、reverse()----將數(shù)組反序，直接在原數(shù)組上修改；

arr = [4,5,2,3,1];
result = arr.reverse()
console.log(arr);   //[1, 3, 2, 5, 4]
console.log(result)   //[1, 3, 2, 5, 4]

9、slice(startIndex,endIndex)----截取起始索引startIndex 到 結(jié)束索引endIndex之間的項(xiàng)組成新的數(shù)組，該新數(shù)組包括起始索引startIndex所對(duì)應(yīng)的項(xiàng)，不包括結(jié)束索引endIndex所對(duì)應(yīng)的項(xiàng)；

arr = [1,2,3,4,5];
result1 = arr.slice(2,5);
result2 = arr.slice(2);
console.log(arr)  //[1,2,3,4,5]
console.log(result1)  //[3,4,5]
console.log(result2)  //[3,4,5]

10、join(separator)----將數(shù)組的元素組起一個(gè)字符串，以separator為分隔符，省略的話則用默認(rèn)用逗號(hào)為分隔符，不影響原數(shù)組；

arr= [1,2,3,4,5];
result = arr.join("|");
console.log(arr)  //[1, 2, 3, 4, 5]
console.log(result)  //1|2|3|4|5

11、splice(start,deleteCount,val1,val2,...)----從start位置開(kāi)始刪除deleteCount項(xiàng)，并從該位置起插入val1,val2,... ，直接在原數(shù)組上修改；

arr= [1,2,3,4,5];
result1 = arr.splice(2,2,7,8,9);
console.log(arr);   //[1,2,7,8,9,5]
console.log(result1);  //[3,4]
result2 = arr.splice(0,1);  //同shift
console.log(arr);   //[2,7,8,9,5]
console.log(result2);  //[1]
arr.splice(0,0,-2,-1);   //同unshift
console.log(arr);  //[-2,-1,2,7,8,9,5]
result3 = arr.length;
console.log(result3);  //7
result4 = arr.splice(arr.length-1,1); //同pop
console.log(arr); //[-2,-1,2,7,8,9]
console.log(result4);  //[5]
arr.splice(arr.length,0,6,7);   //同push
console.log(arr);  //[-2,-1,2,7,8,9,6,7]
result5 = arr.length;
console.log(result5)  //8