javaScript数组基本方法

1:shift()删除原数组第一项，并返回删除元素的值；如果数组为空则返回undefined

var a = [1,2,3,4,5];   
var b = a.shift(); //a:[2,3,4,5] b:1

 

2:unshift()将参数添加到原数组开头，并返回数组的长度

var a = [1,2,3,4,5];   
var b = a.unshift(-2,-1); //a:[-2,-1,1,2,3,4,5] b:7

 

3:pop:删除原数组最后一项，并返回删除元素的值；如果数组为空则返回undefined

var a = [1,2,3,4,5];   
var b = a.pop(); //a:[1,2,3,4] b:5

 

4:push:将参数添加到原数组末尾，并返回数组的长度

var a = [1,2,3,4,5];   
var b = a.push(6,7); //a:[1,2,3,4,5,6,7] b:7

 

5:concat:返回一个新数组，是将参数添加到原数组中构成的

var a = [1,2,3,4,5];   
var b = a.concat(6,7); //a:[1,2,3,4,5] b:[1,2,3,4,5,6,7]

 

6:splice(start,deleteCount,val1,val2,...):从start位置开始删除deleteCount项(个数)，并从该位置起插入val1,val2,...

var a = [1,2,3,4,5];   
var b = a.splice(2,2,7,8,9); //a:[1,2,7,8,9,5] b:[3,4]   
var b = a.splice(0,1); //同shift   
a.splice(0,0,-2,-1); var b = a.length; //同unshift   
var b = a.splice(a.length-1,1); //同pop   
a.splice(a.length,0,6,7); var b = a.length; //同push

 

7：reverse:将数组反序

var a = [1,2,3,4,5];   
var b = a.reverse(); //a:[5,4,3,2,1] b:[5,4,3,2,1]

 

8:sort(orderfunction):按指定的参数对数组进行排序

var a = [1,2,3,4,5];   
var b = a.sort(); //a:[1,2,3,4,5] b:[1,2,3,4,5]

 

9:slice(start,end):返回从原数组中指定开始下标到结束下标之间的项组成的新数组

var a = [1,2,3,4,5];   
var b = a.slice(2,5); //a:[1,2,3,4,5] b:[3,4,5]

 

10:join(separator):将数组的元素组起一个字符串，以separator为分隔符，省略的话则用默认用逗号为分隔符

var a = [1,2,3,4,5];   
var b = a.join("|"); //a:[1,2,3,4,5] b:"1|2|3|4|5"