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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])
- // }
- /* forEach() 方法用于调用数组的每个元素，并将元素传递给回调函数。 */
- /* arr.forEach((ele,index)=>{
- console.log(ele,index)
- }) */
- /* filter 过滤 过滤出符合条件的 */
- /* 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中的每个元素 返回处理后的数组 */
- /* var arr5 = arr.map((ele)=>{
- return ele * 2 + 3
- })
- console.log(arr5)
- console.log(arr) */
- /* some 检测数组当中的元素是否有符合指定条件的 */
- var age = [3,12,18,20,22]
- /* var age1 = age.some((ele)=>{
- return ele >= 23
- })
- console.log(age1) */
- /* evey 检测数组当中的所有元素是否都符合指定条件 */
- /* var age2 = age.every((ele)=>{
- return ele >= 3
- })
- console.log(age2) */
- /* ruduce 将数组内的元素计算为一个值 从左到右 */
- var num = [88,44,22,18,33]
- /* var nums = num.reduce((total,num)=>{
- return total + num
- })
- console.log(nums) */
- /* find 在数组内找到第一个满足条件的元素 */
- /* var num1 = num.find((ele)=>{
- return ele < 23
- })
- console.log(num1) */
- var aLi = document.getElementsByTagName('li')
- console.log(aLi)
- /* var a = [...aLi]
- console.log(a) */
- var a = Array.from(aLi)
- console.log(a)
- /*
- 类数组 转化为数组
- 1.扩展运算符
- 2.Array.from()
- */
- </script>
- </body>
- </html>
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