lovecoding
/
VIP22


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
  </ul>
  <script>
    var arr = [1,2,3,4]
    // for(var i=0;i<arr.length;i++){
    //   console.log(arr[i])
    // }
      /* arr.forEach() */
    arr.forEach((ele,index)=>{
      console.log(ele,index)
    })
    /* filter 过滤 过滤出符合条件 */
    var arr2 = arr.filter((ele)=>{
      return ele > 2
    })
    console.log(arr2)

    var arr3 = [{
      name:'zs',
      age:18
    },{
      name:'lisi',
      age:20
    },{
      name:'ww',
      age:30
    }]

    var arr4 = arr3.filter((ele)=>{
      return ele.age > 19
    })
    console.log(arr4)

    /* map 映射出一个新数组  通过指定函数处理数组当中的每个元素，并返回处理后的数组 */
    var arr5 = arr.map((ele)=>{
      return ele*2+3
    })
    console.log(arr)
    console.log(arr5)

    /* some  检测元素当中是否符合指定条件的元素 */
    var age = [6,10,12,18]
    // var ages = age.some((ele)=>{
    //   return ele>=20
    // })
    // console.log(ages)
    
    /* every 检测数值元素中每个元素都是否符合指定条件 */
    var ages = age.every((ele)=>{
      return ele>=6
    })
    console.log(ages)

    /* reduce 计算 将元素从左到右计算为和 */
    var num = [33,55,66,99]
    var nums = num.reduce((total,num)=>{
      return total + num
    })
    console.log(nums)
    /* find()返回条件下数组的第一个元素的值 */
    var num1 = num.find((ele)=>{
      return ele > 54
    })
    console.log(num1)

    var aLi = document.getElementsByTagName('li')
    console.log(aLi)

    /* 
      类数组 转化为数组
      1、扩展运算符
      2、Array.from()
    */
    // var arrn = [...aLi]
    // console.log(arrn)

    var arrn = Array.from(aLi)
    console.log(arrn)
  </script>
</body>
</html>