JS数组与字符串用法

一、数组用法

数组可以有包含任意数据类型

var a1 = [1, 3.14, ‘Hello’, null, true, new Date()];

可通过索引读取/修改对应元素，'hello’修改为false值

a1[2] = false;

求数组长度 var n = a1.length // n=6

2.数组遍历

for (var i = 0; i < a1.length; i++) { console.log(a1[i]); }

a1.forEach(function(x){ console.log(x); }) 3.进栈出栈 var a3 = [1, 2]; a3.push(‘A’, ‘B’);//进堆a3 = [1, 2, ‘A’, ‘B’] var p = a3.pop(); //出栈 a3= [1, 2, ‘A’] p=‘B’

4.添加删除 var a4 = [1, 2];

a4.unshift(‘A’, ‘B’);在数组头部添加若干元素

arr = [‘A’, ‘B’, 1, 2]

var q = a4.shift(); 把数组第一个元素删除掉 arr = [‘B’, 1, 2] q = ‘A’ 5.排序反转 var a5 = [‘Big’, ‘Cat’, ‘Apple’, ‘big’]; 排序 a5.sort(); a5=[“Apple”, “Big”, “Cat”, “big”] 反转 a5.reverse(); a5=[“big”, “Cat”, “Big”, “Apple”] 二、字符串用法 var s=“How are you?”; var n = s.indexOf(‘a’); //n=4取子串，索引1至3止(不含) ss=“ow”

var ss = s.substring(1,3);

用空格分割字符串

var arr = s.split(" "); arr=[“How”, “are”, “you?”]