Adding HTML5 Validation to Visual Studio

Visual Studio 2012 and later versions include built-in IntelliSense and validation support for HTML5. Visual Studio 2010 had basic IntelliSense support for HTML5, but VS 2012 added corresponding code snippets, making it faster and easier to write HTML5 markup.

Enabling HTML5 Validation in Visual Studio

Follow these steps to enable HTML5 validation −

1. Launch Visual Studio 2012 (or later).
2. Go to Tools > Options from the menu bar.
3. In the Options dialog, navigate to Text Editor > HTML > Validation.
4. In the Target dropdown, select HTML5.
5. Click OK to apply the changes.

Once enabled, Visual Studio will validate your HTML markup against the HTML5 specification and highlight any errors or warnings directly in the editor.

HTML5 Validation in Modern Visual Studio Versions

In Visual Studio 2017, 2019, 2022, and later, HTML5 validation is enabled by default. You do not need to change any settings − the editor automatically validates HTML5 and provides IntelliSense for HTML5 elements, attributes, and ARIA roles.

You can verify or change the validation target by following the same path −

Tools > Options > Text Editor > HTML (Web Forms) > Validation > Target: HTML5

What HTML5 Validation Provides

When HTML5 validation is enabled, Visual Studio offers the following features −

• Error highlighting − Invalid HTML5 tags or attributes are underlined with squiggly lines.
• IntelliSense − Auto-completion for HTML5 elements like <canvas>, <video>, <audio>, <section>, <article>, etc.
• Attribute suggestions − Context-aware suggestions for HTML5-specific attributes such as placeholder, required, autofocus, and data-*.
• Snippet support − Code snippets for quickly inserting common HTML5 structures.

Conclusion

HTML5 validation can be enabled in Visual Studio through Tools > Options > Text Editor > HTML > Validation. In modern versions of Visual Studio (2017+), HTML5 validation and IntelliSense are enabled by default.