Basic usage of js querySelector() (graphic tutorial)
querySelector() method only returns the first element matching the specified selector. If you need to return all elements, please use the querySelectorAll() method instead
querySelector Definition and Usage
querySelector() method returns the elements in the document that match the specified CSS selector an element.
Note: The querySelector() method only returns the first element matching the specified selector. If you need to return all elements, use the querySelectorAll() method instead.
Browser support
The number in the table indicates the version number of the first browser that supports this method.
Syntaxdocument.querySelector(CSS selectors)
Parameter value
Parameter
##CSS Selector String Required. CSS selector that specifies one or more matching elements. Elements can be selected using their id, class, type, attribute, attribute value, etc. For multiple selectors, separate them with commas and return a matching element.
##DOM version: Selectors Level 1 Document Object
Return value: Matches the specified CSS selection The first element of the container. If not found, returns null. If an illegal selector is specified, a SYNTAX_ERR exception is thrown.
Example:
Get the first element with id="demo" in the document: <p id="demo">id="demo" 的 p 元素</p>
<p id="demo">id="demo" 的 p 元素</p>
<p> 点击按钮修改过第一个 id="demo" 的 p元素内容</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction() {
document.querySelector("#demo").innerHTML = "Hello World!";
}
</script>
element in the document:
<p>这是一个 p 与元素。</p>
<p>这也是一个 p 与元素。</p>
<p>点击按钮修改文档中第一个 p 元素的背景颜色。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction() {
document.querySelector("p").style.backgroundColor = "red";
}
</script><h2 class="example">class="example" 的标题</h2>
<p class="example"> class="example" 的段落。</p>
<p>点击按钮为第一个 class="example" 的元素添加背景颜色。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction() {
document.querySelector(".example").style.backgroundColor = "red";
}
</script>element of ="example":
<h2 class="example">class="example" 的标题</h2>
<p class="example">class="example" 的段落。</p>
<p>点击按钮为第一个带有 class="example" 的 p 元素添加背景颜色。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction() {
document.querySelector("p.example").style.backgroundColor = "red";
}
</script><!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>脚本之家</title>
<style>
a[target] {
background-color: yellow;
}
</style>
</head>
<body>
<p> CSS 选择器 a[target] 确保所有有 target 属性的链接背景颜色为黄色：</p>
<a href="//www.jb51.net">jb51.net</a>
<a href="//www.disney.com" target="_blank">disney.com</a>
<a href="//www.wikipedia.org" target="_top">wikipedia.org</a>
<p>点击按钮为带有 target 属性的链接添加红色背景。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction() {
document.querySelector("a[target]").style.border = "10px solid red";
}
</script>
</body>
</html>Suppose you select two selectors:
and elements. The following code will add a background color to the first element in the document:
element in the document:
<h2> h2 元素</h2>
<h3> h3 元素</h3>
<script>
document.querySelector("h2,h3").style.backgroundColor = "red";
</script>6. However, if the
element is before the element in the document, < The h3> element will be set to the specified background color.
<h3> h3 元素</h3>
<h2> h2 元素</h2>
<script>
document.querySelector("h2, h3").style.backgroundColor = "red";
</script>Copy after login7. Realize URL jump by getting the selected content
<h3> h3 元素</h3>
<h2> h2 元素</h2>
<script>
document.querySelector("h2, h3").style.backgroundColor = "red";
</script><select id="language-picker">
<option value="cs">Česky</option>
<option value="en">English</option>
<option value="es">Español</option>
<option value="fr">Français</option>
<option value="jp">日本語</option>
<option value="pl">Polski</option>
<option value="pt">Português</option>
<option value="zh" selected>中国的</option>
</select>
<script>
var lang = document.querySelector('#language-picker');
lang.addEventListener('change', function(e) {
if (e.target.value === 'en') {
window.location = '/';
} else {
window.location = '/' + e.target.value;
}
});
</script>Loading jquery in JS.
jsDetailed method explanation##JS synchronization, Summary of asynchronous and lazy loading implementation
Detailed explanation of JS's method of generating random numbers and random sequences in a specified range
The above is the detailed content of Basic usage of js querySelector() (graphic tutorial). For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to use DirectX repair tool? Detailed usage of DirectX repair tool
Mar 15, 2024 am 08:31 AM
The DirectX repair tool is a professional system tool. Its main function is to detect the DirectX status of the current system. If an abnormality is found, it can be repaired directly. There may be many users who don’t know how to use the DirectX repair tool. Let’s take a look at the detailed tutorial below. 1. Use repair tool software to perform repair detection. 2. If it prompts that there is an abnormal problem in the C++ component after the repair is completed, please click the Cancel button, and then click the Tools menu bar. 3. Click the Options button, select the extension, and click the Start Extension button. 4. After the expansion is completed, re-detect and repair it. 5. If the problem is still not solved after the repair tool operation is completed, you can try to uninstall and reinstall the program that reported the error.
Introduction to HTTP 525 status code: explore its definition and application
Feb 18, 2024 pm 10:12 PM
Introduction to HTTP 525 status code: Understand its definition and usage HTTP (HypertextTransferProtocol) 525 status code means that an error occurred on the server during the SSL handshake, resulting in the inability to establish a secure connection. The server returns this status code when an error occurs during the Transport Layer Security (TLS) handshake. This status code falls into the server error category and usually indicates a server configuration or setup problem. When the client tries to connect to the server via HTTPS, the server has no
How to use Baidu Netdisk-How to use Baidu Netdisk
Mar 04, 2024 pm 09:28 PM
Many friends still don’t know how to use Baidu Netdisk, so the editor will explain how to use Baidu Netdisk below. If you are in need, hurry up and take a look. I believe it will be helpful to everyone. Step 1: Log in directly after installing Baidu Netdisk (as shown in the picture); Step 2: Then select "My Sharing" and "Transfer List" according to the page prompts (as shown in the picture); Step 3: In "Friend Sharing", you can share pictures and files directly with friends (as shown in the picture); Step 4: Then select "Share" and then select computer files or network disk files (as shown in the picture); Fifth Step 1: Then you can find friends (as shown in the picture); Step 6: You can also find the functions you need in the "Function Treasure Box" (as shown in the picture). The above is the editor’s opinion
What is the KMS activation tool? How to use the KMS activation tool? How to use KMS activation tool?
Mar 18, 2024 am 11:07 AM
The KMS Activation Tool is a software tool used to activate Microsoft Windows and Office products. KMS is the abbreviation of KeyManagementService, which is key management service. The KMS activation tool simulates the functions of the KMS server so that the computer can connect to the virtual KMS server to activate Windows and Office products. The KMS activation tool is small in size and powerful in function. It can be permanently activated with one click. It can activate any version of the window system and any version of Office software without being connected to the Internet. It is currently the most successful and frequently updated Windows activation tool. Today I will introduce it Let me introduce to you the kms activation work
Learn to copy and paste quickly
Feb 18, 2024 pm 03:25 PM
How to use the copy-paste shortcut keys Copy-paste is an operation we often encounter when using computers every day. In order to improve work efficiency, it is very important to master the copy and paste shortcut keys. This article will introduce some commonly used copy and paste shortcut keys to help readers perform copy and paste operations more conveniently. Copy shortcut key: Ctrl+CCtrl+C is the shortcut key for copying. By holding down the Ctrl key and then pressing the C key, you can copy the selected text, files, pictures, etc. to the clipboard. To use this shortcut key,
How to merge cells using shortcut keys
Feb 26, 2024 am 10:27 AM
How to use the shortcut keys for merging cells In daily work, we often need to edit and format tables. Merging cells is a common operation that can merge multiple adjacent cells into one cell to improve the beauty of the table and the information display effect. In mainstream spreadsheet software such as Microsoft Excel and Google Sheets, the operation of merging cells is very simple and can be achieved through shortcut keys. The following will introduce the shortcut key usage for merging cells in these two software. exist
How to use potplayer-How to use potplayer
Mar 04, 2024 pm 06:10 PM
Potplayer is a very powerful media player, but many friends still don’t know how to use potplayer. Today I will introduce how to use potplayer in detail, hoping to help everyone. 1. PotPlayer shortcut keys. The default common shortcut keys for PotPlayer player are as follows: (1) Play/pause: space (2) Volume: mouse wheel, up and down arrow keys (3) forward/backward: left and right arrow keys (4) bookmark: P- Add bookmarks, H-view bookmarks (5) full screen/restore: Enter (6) multiple speeds: C-accelerate, 7) Previous/next frame: D/
What is PyCharm? Function introduction and detailed explanation of usage
Feb 20, 2024 am 09:21 AM
PyCharm is a professional Python integrated development environment (IDE) developed by JetBrains. It provides Python developers with powerful functions and tools, making writing Python code more efficient and convenient. PyCharm supports multiple operating systems, including Windows, macOS and Linux, and also supports multiple Python versions, and provides a wealth of plug-ins and extension functions to facilitate developers to customize the IDE environment according to their own needs. P
