字符串
新增两个字符串方法
startsWith()
字符串首开通检测
endsWith()
后缀名检测
includes ()
字符串中是否包含
字符串模板
数组
let title = '头部'let content = '内容'let a = '\';console.log(a)let b = `'+title+'
\ '+content+'\
` console.log(b);${ title }
${ content }
- 将内容可以直接放入字符串里
可以换行
- map--映射
- reduce--汇总
- filter--过滤器
forEach--迭代(循环)
map
- 一个对一个
- 格式:数组
let arr= [55 ,30,61,25,99,55]let res = arr.map(item=>item>=60?'及格':'不及格')console.log(arr,res)
reduce
- 一堆出来一个,汇总
- tmp: 上一个的和
- item 本身
- index下标
let arr1 = [54,45,88,86]let arr2 = arr1.reduce(function(tmp,item,index){ return tmp + item})var result = arr1.reduce((tmp,item,index)=>{ if(index != arr1.length - 1){ return tmp + item }else{ return (tmp + item)/arr1.length }})//alert(result)//68.25// this 指向windowlet result2 = arr1.reduce((tmp,item,index)=>{ if(index != this.length - 1){ return tmp + item }else{ return (tmp + item) / this.length }})alert(result2)//273
filter
let arr1 = [54,45,88,86]// 注:这里的%必须是这个let go = arr1.filter(item=>{ if(item % 3 == 0){ return true }else{ return false }})alert(go)let b = arr1.filter(item=>{item % 3 == 0)alert(b)let arr = [ {title:'2',price:1}, {title:'3',price:5}, {title:'4',price:55}, {title:'5',price:2}]let a = arr.filter(function(json){ return json.title == 4})console.log(a)