Javascript - Introduction
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.
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
functionkeyword.
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:
<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>The above is the detailed content of Javascript - Introduction. For more information, please follow other related articles on the PHP Chinese website!
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