Javascript - Introduction-JS Tutorial-php.cn

Javascript - Introduction

Linda Hamilton

Release： 2025-01-21 14:37:12

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JavaScript: the soul language of web development

JavaScript is the most popular programming language in the world and the cornerstone of the Web. It is easy to learn, is a dynamically typed programming language, and is widely used by developers to create interactive web pages.

Javascript - Introduction

Reason for learning JavaScript:

JavaScript is one of three languages that all web developers must master:

HTML: Define web page content (structure)
CSS: Specify web page layout (style)
JavaScript: Programming web page behavior (function)

JavaScript is supported by almost all browsers.

Reference:https://www.php.cn/link/751d8d469b4f5508690047d65cbdac1b

Application fields of JavaScript:

Web Development
Front-end and back-end development
Game Development
Desktop App
Live Apps
AI and Machine Learning

How to use JavaScript?

There are two main ways to introduce JavaScript: internal JavaScript and external JavaScript.

a) Internal JavaScript

Internal JavaScript refers to embedding JavaScript code directly within the <script> tag in the HTML file. The tag can be placed in the <head> or <body> tag. This method is suitable for small scripts on a single page.

b) External JavaScript

External JavaScript refers to writing JavaScript code into a separate file with the extension .js, and then linking it to the HTML file through the <script> attribute of the src tag.

Syntax:

(an example of <script src="your_script.js"></script> should be added here)

JavaScript functions and events:

A function is an executable block of JavaScript code that can be executed when "called".
A function is a set of instructions or a reusable block of code that performs a specific task and is given a name.
Functions are defined using the function keyword.

For example, a function can be called when an event occurs (such as the user clicking a button).

Event: An event is some kind of action or event that occurs in the browser.

Example:

<code class="language-html"><meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Javascript</title>
<script>
    function payilagam(){
        document.getElementById("welcome").innerHTML = "Welcome to Payilagam";
    }
</script>
<h1></h1>
<p>Output:</p>
<p><button onclick="payilagam()">点击我</button></p>
<p id="welcome"></p>

<p><img src="/uploads/20250121/1737440961678f3ec19d3b4.jpg" alt="Image description" width="800" height="203" loading="lazy"></p></code>

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