Include js file in html same folder

Question

I have some basic html below, and for some reason it's not recognizing the js file I linked in the script tag. Am I linking it incorrectly in some way?:

Nội dung chính Show

First, What Is JavaScript?
Including the JavaScript
The Script Tag
Using the script tag to include an external JavaScript file
JavaScript Files
Simple Demo of Including JavaScript
Other People's JavaScript
JavaScript Frameworks
JavaScript File Sizes
How do I include a JavaScript file in HTML?
Can you include JavaScript in HTML?
How do I link another JavaScript file in HTML?
Can I write JavaScript both within HTML and also as a separate file?

<html>
  <head>
    <link rel="stylesheet" src="/index.css">
    <script src="/index.js"></script>
  </head>
  <body>
    <div id="board">
      <svg id="svg"></svg>
    </div>
  </body>
</html>

Below is the respective index.js:

const grid = [
   [{},{},{},{},{},{},{}],
   [{},{},{},{},{},{},{}],
   [{},{},{},{},{},{},{}],
   [{},{},{},{},{},{},{}],
   [{},{},{},{color: "red"},{color:"black"},{},{}],
];

const render = () =>{
   console.info("rendering?")
   const svg = document.getElementById("svg");
   let doc = ``;
   for (var i=0; i<grid.length; i++) {
      var row = grid[i];
      for (var j=0; j<row.length; j++){
         const square = grid[i][j];
         const color = square && square.color || 'gray';
         doc = doc + `<circle onclick="clickSquare(${i}, ${j})" fill = '${color}' r='30px' cx='${j * 70 + 50}px' cy='${i * 70 + 50}px'> </circle>`;
      }
   }
   svg.innerHTML = doc;
}

window.clickSquare = (x, y) => {
   console.log("You clicked square ", x, y);
}

The ‘src’ attribute in a tag is the path to an external file or resource that you want to link to your HTML document.

For example, if you had your own custom JavaScript file named ‘script.js’ and wanted to add its functionality to your HTML page, you would add it like this:

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Script Src Attribute Example</title>
  </head>
  <body>

  <script src="./script.js"></script>
  </body>
</html>

This would point to a file named ‘script.js’ that is in the same directory as the .html file. You can also link to other directories by using ’..’ in the file path.

<script src="../public/js/script.js"></script>

This jumps up one directory level then into a ‘public’ directory then to a ‘js’ directory and then to the ‘script.js’ file.

You can also use the ‘src’ attribute to link to external .js files hosted by a third party. This is used if you don’t want to download a local copy of the file. Just note that if the link changes or network access is down, then the external file you are linking to won’t work.

This example links to a jQuery file.

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>

More Information:

MDN Article on the HTML

Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started

Back to Class 9 page »

Including JavaScript in your page is a fairly simple process.

First, What Is JavaScript?

From the W3C Schools Site:

JavaScript was designed to add interactivity to HTML pages
JavaScript is a scripting language
A scripting language is a lightweight programming language
JavaScript is usually embedded directly into HTML pages
JavaScript is an interpreted language (means that scripts execute without preliminary compilation)
Everyone can use JavaScript without purchasing a license

Including the JavaScript

You can include JavaScript in your HTML in two ways:

Writing the code in your HTML
Including it as a link to an external file

For the most part, you will include the JavaScript as an external file.

The Script Tag

The <script> tag is what we use to includes our JavaScript. It's a lot like the <link> tag you've already been using to include your CSS files.

Here's a very basic snippet of JavaScript using the script tag. This JavaScript is written directly into our HTML page. It will call and alert box as soon as the page loads.

<script type="text/javascript">
  alert("This alert box was called with the onload event");
</script>

When using the script tag, we must always use the attribute name and value of type="text/javascript".

Using the script tag to include an external JavaScript file

To include an external JavaScript file, we can use the script tag with the attribute src. You've already used the src attribute when using images. The value for the src attribute should be the path to your JavaScript file.

<script type="text/javascript" src="path-to-javascript-file.js"></script>

This script tag should be included between the <head> tags in your HTML document.

JavaScript Files

JavaScript files are not HTML files or CSS files.

Always end with the js extension
Only include JavaScript

It's customary to put all JavaScript files in a folder called js on websites, like so:

Simple Demo of Including JavaScript

Here's a very simple demonstration of how to include an external JavaScript file into an HTML page.

Basic JavaScript Example

Other People's JavaScript

For this class you are not expected to write any actual JavaScript code. Lucky for you, many of people have already written lots of JavaScript and even allow you to use it for free.

JavaScript Frameworks

A Framework is basically a library of code for a certain language. Generally, the framework abstracts common tasks and makes it easier and faster for designers and developers to write their specific code. Frameworks don't really do anything by themselves, they just provide an easier platform for people to build on.

Common JavaScript Frameworks:

JQuery
Prototype
MooTools
script.aculo.us

Of these frameworks, JQuery is currently the most popular one. It's also the one you're most like to encounter being used as a buzz word.

JavaScript File Sizes

Many JavaScript files can tend to be rather large, which can slow down the load time of your page. Popular frameworks usually offer a "minified" version of their code. You should always use this version in your pages because it will have a smaller file size.

Back to Class 9 page »

How do I include a JavaScript file in HTML?

To include an external JavaScript file, we can use the script tag with the attribute src . You've already used the src attribute when using images. The value for the src attribute should be the path to your JavaScript file. This script tag should be included between the <head> tags in your HTML document.

Can you include JavaScript in HTML?

You can add JavaScript code in an HTML document by employing the dedicated HTML tag <script> that wraps around JavaScript code. The <script> tag can be placed in the <head> section of your HTML or in the <body> section, depending on when you want the JavaScript to load.

How do I link another JavaScript file in HTML?

Save the script file with a .js extension, and then refer to it using the src attribute in the <script> tag. Note: The external script file cannot contain the <script> tag. Note: Point to the external script file exactly where you would have written the script.

Can I write JavaScript both within HTML and also as a separate file?

JavaScript in <head> or <body> You can place any number of scripts in an HTML document. Scripts can be placed in the <body> , or in the <head> section of an HTML page, or in both.

programming html Javascript src path