# As-You-Type Checking

> Underline misspelled words as users type in a WPF TextControl with a TXSpellChecker resource in XAML, and validate a TextBox with a spelling ValidationRule.

- **Product:** TX Spell .NET for WPF
- **Section:** Documentation
- **Kind:** Topic
- **Path:** TX Spell .NET for WPF > Spell Checking > As-You-Type Checking
- **Web URL:** https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/
- **LLMs URL:** https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/llms.txt
- **LLMs-Full URL:** https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/llms-full.txt

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## On This Page

- [How As-You-Type Checking Works](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#how-as-you-type-checking-works)
- [Connect the Spell Checker in XAML](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#connect-the-spell-checker-in-xaml)
- [Use the Spell Checker in Code](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#use-the-spell-checker-in-code)
- [What the User Sees](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#what-the-user-sees)
- [Control What Is Checked and Shown](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#control-what-is-checked-and-shown)
- [Validate a TextBox as the User Types](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#validate-a-textbox-as-the-user-types)
- [Next Steps](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/as-you-type/#next-steps)

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## Nearby

- **Previous:** [Spell Checking](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/llms.txt)
- **Next:** [Checking on Demand](https://docs.textcontrol.com/tx-spell-dotnet-wpf/spell-checking/on-demand/llms.txt)