HTML Guide
The charset attribute on a <script> element can be used to specify the character encoding of an external script, whose URL should be specified on the src attribute.
If the script is not external, then the charset attribute should not be used, as the character encoding of the HTML document will be used.
Learn more:
Related W3C validator issues
The <script> tag allows authors to include dynamic scripts and data blocks in their documents. When the src is present, this tag accepts a type attribute which must be either:
- an empty string
- text/javascript (that’s the default, so it can be omitted)
- module
Examples:
<!-- This is valid, without a type it defaults to JavaScript -->
<script src="app.js"></script>
<!-- This is valid, but will warn that it can be omitted -->
<script type="text/javascript" src="app.js"></script>
<!-- An empty attribute is valid, but will warn that it can be omitted -->
<script type="" src="app.js"></script>
<!-- The module keyword is also valid as a type -->
<script type="module" src="app.js"></script>
<!-- Any other type is invalid -->
<script type="wrong" src="app.js"></script>
<script type="text/html" src="app.js"></script>
<script type="image/jpeg" src="app.js"></script>Ensure the src attribute on the script element is non-empty and points to a valid resource.
The src attribute in a script element specifies the URL of an external script file. An empty src attribute is invalid because it tells the browser to fetch a resource from a URL that is not provided, leading to loading errors. Instead, ensure that the src attribute contains a valid file path or URL to an existing script file. If the script content is meant to be inline, you should omit the src attribute altogether and include the script content directly within the script element.
Example of a Valid External Script
Here is a valid example of a script element with a non-empty src attribute:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Valid Script Example</title>
</head>
<body>
<script src="path/to/script.js"></script>
</body>
</html>Example of a Valid Inline Script
If the script is to be written inline, exclude the src attribute and write the JavaScript code directly within the script tags:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Inline Script Example</title>
</head>
<body>
<script>
console.log('This is an inline script.');
</script>
</body>
</html>Troubleshooting
Double-check the script’s file path:
- Ensure the file path you provide in the src is correct relative to the HTML file.
- Make sure the script file exists in the location specified.
- If using a network URL, verify that the URL is correct and accessible.
The issue arises from the space character in the src attribute value of the script element. In URLs, spaces are not allowed and should be properly encoded to avoid validation errors.
Fix
Replace spaces with %20, which is the URL-encoded representation of a space.
Example
Before:
<script src="https://example.com/media assets/app.js"></script>After:
<script src="https://example.com/media%20assets/app.js"></script>Explanation
In this example, the space between “media” and “assets” in the URL is replaced with %20. This change ensures that the URL conforms to standards and is correctly processed by browsers and servers. Spaces and other special characters in URLs must be encoded to ensure proper formatting and accessibility.
The async and defer boolean attributes of the <script> element control how an external script should be executed once it has been downloaded. The async attribute makes sense when an external script (defined with the src attribute) is loaded, or when defining a script of type module:
<script async src="app.js"></script>
<script async type="module">
/* JavaScript module code here */
</script>The defer and async boolean attributes of the <script> element control how an external script should be executed once it has been downloaded. These attributes only make sense when referring to external scripts, so a src attribute must also be present to specify the location of the script.
Example:
<script defer src="app.js"></script>If your script is not external, and is inlined within the HTML document, then you should remove the defer attribute, like in this example:
<script>
console.log("hello");
</script>A <script> element has been found that is using the now obsolete charset attribute. You can safely remove this attribute.
For example, this is using both type and charset attributes, with their default values. Both can be removed:
<script src="app.js" type="text/javascript" charset="UTF-8"></script>and just use this:
<script src="app.js"></script>The <meta charset> is expected to appear at the beginning of the document, within the first 1024 bytes. Consider moving it to the beginning of the <head> section, as in this example:
<head>
<meta charset="utf-8">
...
</head>A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified. For HTML documents, the standard way to declare a document character encoding is by including a <meta> tag with a charset attribute, typically <meta charset="utf-8">.
According to the W3C standard:
The element containing the character encoding declaration must be serialized completely within the first 1024 bytes of the document.
In order to define the charset encoding of an HTML document, both of these options are valid, but only one of them must appear in the document:
<!-- This is the preferred way -->
<meta charset="UTF-8">
<!-- This is the older way, also valid -->
<meta http-equiv="content-type" content="text/html; charset=UTF-8">The <meta charset> tag, used to define the character encoding, must appear only once in a document, within the <head> section.
The combination of type="module" and defer is not allowed. The type="module" attribute itself implies that the script should be executed in a deferred way, hence using the defer attribute is unnecessary and invalid.
Steps to Fix the Issue:
- Remove the defer Attribute: When you use type="module", you should not include the defer attribute since module scripts defer automatically.
Incorrect Code:
<script type="module" defer src="example.js"></script>Corrected Code:
<script type="module" src="example.js"></script>