jQuery 选择器


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jQuery 与 JavaScript

jQuery 由 John Resig 于 2006 年创建。 它旨在处理浏览器不兼容性并简化 HTML DOM 操作、事件处理、动画和 Ajax。

十多年来,jQuery 一直是世界上最流行的 JavaScript 库。

然而,在 JavaScript 版本 5(2009)之后,大多数 jQuery 实用程序都可以通过几行标准 JavaScript 来解决:


通过 ID 查找 HTML 元素

返回 id="id01" 的元素:

jQuery

myElement = $("#id01");

自己尝试一下 →

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
</head>
<body>

<h2>Finding HTML Elements by Id</h2>
<p id="id01">Hello World!</p>
<p id="id02">Hello Sweden!</p>
<p id="id03">Hello Japan!</p>

<p id="demo"></p>

<script>
$(document).ready(function() {
  var myElements = $("#id01");
  $("#demo").text("The text from the id01 paragraph is: " + myElements[0].innerHTML);
});
</script>

</body>
</html>

JavaScript

myElement = document.getElementById("id01");

自己尝试一下 →

<!DOCTYPE html>
<html>
<body>

<h2>Finding HTML Elements by Id</h2>
<p id="id01">Hello World!</p>
<p id="id02">Hello Sweden!</p>
<p id="id03">Hello Japan!</p>

<p id="demo"></p>

<script>
const myElement = document.getElementById("id01");
document.getElementById("demo").innerHTML = "The text from the id01 paragraph is: " + myElement.innerHTML;
</script>

</body>
</html>

通过标签名称查找 HTML 元素

返回所有 <p> 元素:

jQuery

myElements = $("p");

自己尝试一下 →

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
</head>

<body>

<h2>Finding HTML Elements by Tag Name</h2>

<p>Hello World!</p>
<p>Hello Sweden!</p>
<p>Hello Japan!</p>

<p id="demo"></p>

<script>
$(document).ready(function() {
  var myElements = $("p");
  $("#demo").text("The text in the first paragraph is: " + myElements[0].innerHTML);
});
</script>

</body>
</html>

JavaScript

myElements = document.getElementsByTagName("p");

自己尝试一下 →

<!DOCTYPE html>
<html>
<body>

<h2>Finding HTML Elements by Tag Name</h2>
<p>Hello World!</p>
<p>Hello Sweden!</p>
<p>Hello Japan!</p>

<p id="demo"></p>

<script>
const myElements = document.getElementsByTagName("p");
document.getElementById("demo").innerHTML = "The text in the first paragraph is: " + myElements[0].innerHTML;
</script>

</body>
</html>


通过类名查找 HTML 元素

返回所有带有 class="intro" 的元素。

jQuery

myElements = $(".intro");

自己尝试一下 →

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
</head>
<body>

<h2>Finding HTML Elements by Class Name</h2>

<p class="intro">Hello World!</p>
<p class="intro">Hello Sweden!</p>
<p class="intro">Hello Japan!</p>

<p id="demo"></p>

<script>
$(document).ready(function() {
  var myElements = $(".intro");
  $("#demo").text("The first paragraph with class='intro' is: " + myElements[0].innerHTML);
});
</script>

</body>
</html>

JavaScript

myElements = document.getElementsByClassName("intro");

自己尝试一下 →

<!DOCTYPE html>
<html>
<body>

<h2>Finding HTML Elements by Class Name</h2>
<p class="intro">Hello World!</p>
<p class="intro">Hello Sweden!</p>
<p class="intro">Hello Japan!</p>

<p id="demo"></p>

<script>
const myElements = document.getElementsByClassName("intro");
document.getElementById("demo").innerHTML = "The first paragraph with class='intro' is: " + myElements[0].innerHTML;
</script>

</body>
</html>

通过 CSS 选择器查找 HTML 元素

返回所有带有 class="intro" 的 <p> 元素的列表。

jQuery

myElements = $("p.intro");

自己尝试一下 →

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
</head>
<body>

<h2>Finding HTML Elements by Query Selector</h2>

<p class="intro">Hello World!</p>
<p class="intro">Hello Sweden!</p>
<p class="intro">Hello Japan!</p>

<p id="demo"></p>

<script>
$(document).ready(function() {
  var myElements = $("p.intro");
  $("#demo").text("The first paragraph with class='intro' is: " + myElements[0].innerHTML);
});
</script>

</body>
</html>

JavaScript

myElements = document.querySelectorAll("p.intro");

自己尝试一下 →

<!DOCTYPE html>
<html>
<body>

<h2>Finding HTML Elements by Query Selector</h2>
<p class="intro">Hello World!</p>
<p class="intro">Hello Sweden!</p>
<p class="intro">Hello Japan!</p>

<p id="demo"></p>

<script>
const myElements = document.querySelectorAll("p.intro");
document.getElementById("demo").innerHTML = 
"The first paragraph with class='intro' is: " + myElements[0].innerHTML;
</script>

</body>
</html>