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Discuss how to connect HTML to JavaScript

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Release： 2023-04-25 10:14:33

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HTML and JavaScript are one of the two most basic and important technologies in Web development. Their combination can improve the interactivity and usability of web pages at the beginning of design. In this article, we'll discuss how to connect HTML to JavaScript to combine the best of both technologies.

1. The basis of HTML

HTML is the basic language of web pages. It defines a markup language used to create web pages. It uses a series of tags and attributes to describe elements in web pages. HTML tags usually consist of an opening tag and a closing tag, which contain content for displaying data. For example, the following code defines a simple HTML web page:

<!DOCTYPE html>
<html>
<head>
    <title>My Page</title>
</head>
<body>
    <h1>Welcome to my page!</h1>
    <p>This is a paragraph of text.</p>
</body>
</html>

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The code contains the basic structure of a simple web page. The DOCTYPE declaration tells the browser that this is an HTML5 document. The html tag contains the entire HTML document and includes two parts: head and body. The head section contains the document's metadata and referenced external files, such as style sheets and script files. The body part contains the real page content, describing the structure and content of the page through various HTML tags (such as h1, p, etc.).

2. The basis of JavaScript

JavaScript is a dynamic programming language that is usually used to add dynamic effects to web pages, improve user experience, and improve website usability. Because it can be directly embedded into HTML, it is known as one of the three cornerstones of web development, the other two being HTML and CSS.

Similar to HTML, JavaScript is also object-oriented and provides various methods and tools to operate elements and events in web pages. For example, the following code defines a simple JS script:

<script>
function showMessage() {
    alert("Hello, world!");
}
</script>

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The code defines a function named showMessage, which when called will pop up a dialog box containing the text "Hello, world!"

3. Connect HTML and JavaScript

To connect HTML to JavaScript, the most common method is to use the script tag. The script tag defines a block of JavaScript code and inserts it into an HTML element. For example, the following code demonstrates how to use JavaScript in an HTML web page:

<!DOCTYPE html>
<html>
<head>
    <title>My Page</title>
    <script>
    function showMessage() {
        alert("Hello, world!");
    }
    </script>
</head>
<body>
    <h1>Welcome to my page!</h1>
    <p>This is a paragraph of text.</p>
    <button onclick="showMessage()">Click me!</button>
</body>
</html>

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In the code, we insert the JavaScript code block into the head tag. In a web page, we use the button tag to create a button. When the button is clicked, the showMessage function is called. At this time, the alert function will pop up a dialog box on the browser, which contains the text "Hello, world!"

In addition to directly using the onclick attribute to call the function, we can also encapsulate the JavaScript code into an external file. Referencing external files in the page can improve the maintainability and readability of the code, which is a good habit when developing complex websites. For example, we can write the showMessage function in a separate JS file:

//myScript.js
function showMessage() {
    alert("Hello, world!");
}

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Subsequently, use the script tag in the HTML file to reference the file:

<!DOCTYPE html>
<html>
<head>
    <title>My Page</title>
    <script src="myScript.js"></script>
</head>
<body>
    <h1>Welcome to my page!</h1>
    <p>This is a paragraph of text.</p>
    <button onclick="showMessage()">Click me!</button>
</body>
</html>

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In the above code, we use src The attribute introduces the myScript.js file into the HTML file, and then the functions in it can be called.

Of course, there are many ways to connect HTML with JavaScript. In actual development, you can choose the method that suits you according to your needs and team specifications.

4. Summary

In this article, we explored how to connect HTML to JavaScript. HTML and JavaScript are one of the two most basic and important technologies for web development. Their combination can provide a substantial increase in the interactivity, usability and user experience of the website. We learned how to embed JavaScript code blocks and functions into HTML elements using script tags and onclick attributes, and how to encapsulate JavaScript code into a separate file, while also noting some pitfalls to avoid in practice. After learning these skills, we can use HTML and JavaScript more flexibly to create richer and more interesting websites.

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