JavaScript code needs to be placed in the web page using the "<script>" tag and run with the help of the browser environment; the syntax is "<script>JS code</script>" or "".
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
JavaScript programs cannot run independently and can only be executed in the host environment. Under normal circumstances, JavaScript code can be placed in the web page and run with the help of the browser environment.
There are two ways to put JavaScript code into a web page:
Method 1: Use the <script> tag to directly embed the code</script>
Embedding JavaScript scripts in HTML pages requires the use of the <script> tag. Users can directly write JavaScript code in the <script> tag. </script>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>第一个JavaScript程序</title>
<script type="text/javascript">
document.write("<h1 id="Hi-JavaScript">Hi,JavaScript!</h1>");
</script>
</head>
<body></body>
</html>
Method 2: Put the JavaScript code into a js file and use the <script> tag to import the js file</script>
JavaScript programs can be placed not only directly in HTML documents, but also in JavaScript files.
JavaScript files are text files with the extension .js and can be edited using any text editor.
JavaScript files cannot run independently and need to be imported into the web page and executed through the browser. JavaScript files can be imported using the <script> tag. </script>
For example: There is a test.js file that contains the following code:
alert("Hi,JavaScript!");Insert a <script> tag within the <head> tag of an HTML file. Define the src attribute and set the attribute value to a URL string pointing to an external JavaScript file. The code is as follows: </script>
<script type="text/javascript" ></script>
Note:
When using the <script> tag to include external JavaScript files, the default file type is Javascript. Therefore, regardless of whether the loaded file has a .js extension or not, the browser will parse it as a JavaScript script. </script>
The <script> tag that defines the src attribute should no longer contain JavaScript code. If the code is embedded, only the external JavaScript file will be downloaded and executed, and the embedded code will be ignored. </script>
Save the HTML file and preview it in the browser:
[Recommended learning: javascript advanced tutorial]
The above is the detailed content of Where to put javascript code. For more information, please follow other related articles on the PHP Chinese website!
The Benefits of React: Performance, Reusability, and MoreApr 15, 2025 am 12:05 AMReact’s popularity includes its performance optimization, component reuse and a rich ecosystem. 1. Performance optimization achieves efficient updates through virtual DOM and diffing mechanisms. 2. Component Reuse Reduces duplicate code by reusable components. 3. Rich ecosystem and one-way data flow enhance the development experience.
React: Creating Dynamic and Interactive User InterfacesApr 14, 2025 am 12:08 AMReact is the tool of choice for building dynamic and interactive user interfaces. 1) Componentization and JSX make UI splitting and reusing simple. 2) State management is implemented through the useState hook to trigger UI updates. 3) The event processing mechanism responds to user interaction and improves user experience.
React vs. Backend Frameworks: A ComparisonApr 13, 2025 am 12:06 AMReact is a front-end framework for building user interfaces; a back-end framework is used to build server-side applications. React provides componentized and efficient UI updates, and the backend framework provides a complete backend service solution. When choosing a technology stack, project requirements, team skills, and scalability should be considered.
HTML and React: The Relationship Between Markup and ComponentsApr 12, 2025 am 12:03 AMThe relationship between HTML and React is the core of front-end development, and they jointly build the user interface of modern web applications. 1) HTML defines the content structure and semantics, and React builds a dynamic interface through componentization. 2) React components use JSX syntax to embed HTML to achieve intelligent rendering. 3) Component life cycle manages HTML rendering and updates dynamically according to state and attributes. 4) Use components to optimize HTML structure and improve maintainability. 5) Performance optimization includes avoiding unnecessary rendering, using key attributes, and keeping the component single responsibility.
React and the Frontend: Building Interactive ExperiencesApr 11, 2025 am 12:02 AMReact is the preferred tool for building interactive front-end experiences. 1) React simplifies UI development through componentization and virtual DOM. 2) Components are divided into function components and class components. Function components are simpler and class components provide more life cycle methods. 3) The working principle of React relies on virtual DOM and reconciliation algorithm to improve performance. 4) State management uses useState or this.state, and life cycle methods such as componentDidMount are used for specific logic. 5) Basic usage includes creating components and managing state, and advanced usage involves custom hooks and performance optimization. 6) Common errors include improper status updates and performance issues, debugging skills include using ReactDevTools and Excellent
React and the Frontend Stack: The Tools and TechnologiesApr 10, 2025 am 09:34 AMReact is a JavaScript library for building user interfaces, with its core components and state management. 1) Simplify UI development through componentization and state management. 2) The working principle includes reconciliation and rendering, and optimization can be implemented through React.memo and useMemo. 3) The basic usage is to create and render components, and the advanced usage includes using Hooks and ContextAPI. 4) Common errors such as improper status update, you can use ReactDevTools to debug. 5) Performance optimization includes using React.memo, virtualization lists and CodeSplitting, and keeping code readable and maintainable is best practice.
React's Role in HTML: Enhancing User ExperienceApr 09, 2025 am 12:11 AMReact combines JSX and HTML to improve user experience. 1) JSX embeds HTML to make development more intuitive. 2) The virtual DOM mechanism optimizes performance and reduces DOM operations. 3) Component-based management UI to improve maintainability. 4) State management and event processing enhance interactivity.
React Components: Creating Reusable Elements in HTMLApr 08, 2025 pm 05:53 PMReact components can be defined by functions or classes, encapsulating UI logic and accepting input data through props. 1) Define components: Use functions or classes to return React elements. 2) Rendering component: React calls render method or executes function component. 3) Multiplexing components: pass data through props to build a complex UI. The lifecycle approach of components allows logic to be executed at different stages, improving development efficiency and code maintainability.
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
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
Zend Studio 13.0.1
Powerful PHP integrated development environment
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
