全选反选 · JavaScript

## 全选反选这里写的有问题,更好的去网上搜. 当全选的时候,让子checkbox的状态和父checkbox的状态一致就行了. 在事件函数中用this来获取父checkbox. ``` <body> <input type="checkbox" name="" id="btn"> 全选 <input type="checkbox" name=""> ip1 <input type="checkbox" name=""> ip2 <input type="checkbox" name=""> ip3 <input type="checkbox" name=""> ip4 <input type="button" value="反选" id="btn1"> <script> var btn = document.getElementById('btn'); btn.onclick = function () { var checkboxs = document.getElementsByTagName('input'); for (let i = 0; i < checkboxs.length; i++) { if (checkboxs[i].type == 'checkbox') { var check = checkboxs[i]; check.checked = true; } } } var btn1 = document.getElementById('btn1'); btn1.onclick = function () { var checkboxs = document.getElementsByTagName('input'); for (let i = 0; i < checkboxs.length; i++) { if (checkboxs[i].type == 'checkbox') { if (checkboxs[i].checked == true) { checkboxs[i].checked = false; } else { checkboxs[i].checked = true; } } } } </script> ```