About This HTML Issue
The http-equiv attribute on the <meta> element simulates HTTP response headers. However, the HTML living standard only allows a specific set of values for http-equiv, and Content-Script-Type is not among them. The allowed values include content-type, default-style, refresh, x-ua-compatible, and content-security-policy.
In HTML 4.01, <meta http-equiv="Content-Script-Type" content="text/javascript"> was used to tell the browser which scripting language to assume for inline event handlers (like onclick). Since JavaScript is now the only scripting language supported by browsers, this declaration serves no purpose. Every modern browser already assumes JavaScript by default, making this meta tag completely redundant.
Removing this tag has no effect on your page’s behavior. Your scripts will continue to work exactly as before. If you’re maintaining a legacy codebase, you can safely delete this line during any cleanup or modernization effort.
Examples
❌ Invalid: using Content-Script-Type
<head>
<meta charset="utf-8">
<meta http-equiv="Content-Script-Type" content="text/javascript">
<title>My Page</title>
</head>
This triggers the validation error because Content-Script-Type is not a valid http-equiv value in modern HTML.
✅ Fixed: remove the obsolete meta tag
<head>
<meta charset="utf-8">
<title>My Page</title>
</head>
Simply remove the <meta http-equiv="Content-Script-Type"> line. No replacement is needed — browsers already default to JavaScript for all script handling.
✅ Valid http-equiv values for reference
Here are some examples of http-equiv values that are valid in modern HTML:
<head>
<meta charset="utf-8">
<meta http-equiv="x-ua-compatible" content="IE=edge">
<meta http-equiv="refresh" content="30">
<meta http-equiv="content-security-policy" content="default-src 'self'">
<title>My Page</title>
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