How To Add JavaScript To HTML – An Ultimate Guide

How To Add JavaScript To HTML
5 min read

JavaScript is a programming language, also known as JS. It is used in web development to create advanced and interactive web pages. The word “script” is used for those languages that are not independent, and here it refers to JavaScript, which runs on the client machine. In other words, you can say that the word scripting is used for the languages that require the support of another programming language to get accomplished or executed. This article will guide you on how to add JavaScript to HTML.

JavaScript also executes with the help of HTML or being integrated into HTML code. You can use JavaScript in different ways to generate warning messages,

JavaScript is used in several web pages, such as generating warning messages, building image galleries, document object model manipulation, form authentication, and more.

Advantages of JavaScript

As you know, JavaScript is a scripting language. First, JavaScript is also known as LiveScript. Later on, it is known as JavaScript. Following are some of the best advantages of using JavaScript:

Less Server Interaction

If you want to increase the speed of your website, the best method is to lessen the communication with the server. JavaScript helps in this regard by verifying user input on the client side. After running the initial validation control, it only sends requests to the server. In this way, the number of requests to the server minimizes remarkably.

User-Friendly Interfaces

You can create modern, advanced, and interactive client-side interfaces. For example, you can add sliders, slideshows, drag-and-drop features, etc.

Instant Feedback To The User

If you are using JavaScript, you can ensure that users get instant feedback. For example, if there are two users, one has filled a form, and the other one has left the form empty. They will have to wait for the page to reload without JavaScript validation. However, with JavaScript, they will be changed immediately.

Easy debugging

JavaScript is an interpreted language. It means that written code breaks line by line. If any error occurs, you can see the line number where the error occurs.

How To Add JavaScript To HTML

There are two methods of adding JavaScript to HTML and making them work together. We have seen the advantages of JavaScript; let’s look at some ways we can link JS to HTML.

Adding JavaScript to HTML File

Add JavaScript code in an HTML document by implementing the dedicated HTML tag <script> that completes with JavaScript code.

Place the <script> tag in the <head> section of your HTML or in the <body> section. It depends on when you want the JavaScript to load.

JavaScript code is written in the document <head> section to keep them included and out of the main content of your HTML document.

Within the page’s layout, if your script requires to optimize at a certain point, like when using document.write to create content — you should put it at the point where it should be called, usually within the <body> section.

Let’s ponder upon the following blank HTML document with a browser title of Today’s Date:

Adding JavaScript to HTML File , How To Add JavaScript To HTML

At this point, this file includes only HTML markup. We want to discuss further how to add JavaScript to HTML documents:

Adding JavaScript to HTML File , How To Add JavaScript To HTML

It allows the webpage to show a notification with the current date. You can add a <script> tag with JavaScript code in HTML file.

Add JavaScript code within the <head> tags, pointing to the browser to run the JavaScript code. We can also add JavaScript below the <title> tag as shown below:

Adding JavaScript to HTML File , How To Add JavaScript To HTML

Once the page has loaded, you receive an alert shown below:

 Adding JavaScript to HTML File, How To Add JavaScript To HTML

As you can see in the below example, if you need some changes shown in the body of HTML, we would require that after the <head> section, so that is shown on the page.

Adding JavaScript to HTML File , How To Add JavaScript To HTML

The output of the above code is shown like this:

 seen the advantages of JavaScript; let's look at some ways we can link JS to HTML.  Adding JavaScript to HTML File ,How To Add JavaScript To HTML

Scripts that are no longer and can run only on one page works very well within HTML file, but if the scripts are long and run on more than one page, then it is not a productive or effective solution because larger scripts are challenging to read and understand. We further discuss how to manage separate JavaScript files in HTML documents.

Adding a Separate JavaScript File To HTML Code

Sometimes, it is not suitable to embed JavaScript to HTML directly. Mainly, JS scripts are used on different pages, so it is best to keep JavaScript code in separate files. The most suitable method to add JavaScript to HTML is external file importing. These files can be validated within the HTML documents, just like CSS documents. Here are some benefits of linking JavaScript to HTML separately.

  • When you add JavaScript and HTML code separately, it makes everything easy, maintainable, and reusable.
  • Code readability and maintenance become very easy.
  • Cached JavaScript files enhance overall website performance by decreasing the time taken by pages to load.

Let’s explain a small web project on linking JS files to HTML documents. It includes script.js in the js/ directory, style.css in the CSS/ directory, and a main index.html file in the project’s root.

Adding a Separate JavaScript File To HTML Code , How To Add JavaScript To HTML

We can begin with our previous HTML document from the section above:

 Adding a Separate JavaScript File To HTML Code , How To Add JavaScript To HTML

You will see how JavaScript code shows the date as a <h1> header to the script.file:

Adding a Separate JavaScript File To HTML Code , How To Add JavaScript To HTML

With the help of the following code, You can also add a reference to this script to the <body> section.

How To Add JavaScript To HTML  , Adding a Separate JavaScript File To HTML Code

The <script> tag signifies the script.js file in the js/ directory of our web project. Let’s consider this line in the context of our HTML file within the <body> section:

Adding a Separate JavaScript File To HTML Code , How To Add JavaScript To HTML

You can also edit the style.css file by adding background color and styles to the <h1> header:

Style.css file

You can also reference the CSS file within the <head> section of our HTML document:

Adding a Separate JavaScript File To HTML Code , How To Add JavaScript To HTML

Now, you can load the index.html file on the web browser of your choice with the help of JavaScript and CSS.

Conclusion

In this article, we have discussed how to use JavaScript in HTML. JavaScript can be used in combination with HTML to run modern and advanced web applications that are intuitive, interactive, and user-friendly. Using simple client-side validation reduces server traffic and improves the overall performance and efficiency of the website.

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