先上代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.red{
color: red;
}
</style>
</head>
<body>
<ul>
<li>01</li>
<li>02</li>
<li>03</li>
<li>04</li>
</ul>
<script>
document.querySelector('li:nth-child(1)').οnclick=function () {
if (this.classList.contains('red')){
this.classList.remove('red')
this.classList.remove('underline')
}else {
this.classList.add('red')
this.classList.add('underline')
}
}
document.querySelector('li:nth-child(2)').οnclick=function () {
this.classList.toggle('red');
this.classList.toggle('underline');
}
document.querySelectorAll('li:nth-child(n+3)').forEach(li=>{
li.οnclick=function () {
console.log(this.innerHTML+" clicked")
}
})
</script>
</body>
</html>效果
querySelector(cssSelector)：参数cssSelector为css选择器，返回符合条件的一个dom元素，若没有元素则返回nullquerySelectorAllcssSelector)：参数cssSelector为css选择器，返回所有符合元素的dom元素