题解 | #全选#
全选
https://www.nowcoder.com/practice/84b89f326e3c4e96bacb63296e84623a
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> </head> <style> ul { list-style: none; } </style> <body> <ul> <li>全选<input type='checkbox' id='all'></li> <li>Java<input type='checkbox' class='item'></li> <li>javaScript<input type='checkbox' class='item'></li> <li>C++<input type='checkbox' class='item'></li> <li>python<input type='checkbox' class='item'></li> <li>.net<input type='checkbox' class='item'></li> </ul> <script> // 补全代码 var all = document.querySelector('#all'); var options = Array.from(document.querySelectorAll('.item')); all.onchange = () => { options.forEach(i => i.checked = all.checked) } options.forEach( item =>{ item.onchange = function() { all.checked = options.every(x => x.checked) } }) </script> </body> </html>
注意:类数组对象一定要通过Array.from()将其转化为数组才能用数组的every方法。