Input Masks
Guide people into the expected format without fighting what they type.
What it adds
Formatted input fields that insert separators as the user types, while submitting a clean, normalized value.
What your agent is told to do
6
What your agent is told to do
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Keep the caret where the user expects it after every insertion and deletion. Reformatting that jumps the caret to the end is the single most common failure of masked inputs.
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Accept pasted values in any shape — with separators, without them, with spaces or dashes — and normalize on paste rather than rejecting.
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Submit the normalized value to the server and format only for display. The server must never receive a display string it has to strip.
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Deleting a separator must delete the adjacent character, not fight the user by re-inserting it.
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Do not put the mask pattern in the field's accessible name, and do not let screen readers read every separator character. Announce the field's purpose and expected format once via the label and description.
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Never use a mask as your only validation. The value must be validated server-side regardless of what the field allowed.
Edge cases it handles
6
Edge cases it handles
6- Selecting the whole value and typing over it must reformat cleanly from scratch.
- Undo and redo must step through logical edits, not through each reformat.
- Autofill inserts a whole value at once, bypassing keystroke handlers — normalize on change, not only on keypress.
- Mobile keyboards behave differently; test composition and predictive input rather than assuming key events.
- A partially entered value must be preserved on validation failure, not cleared.
- The field must remain usable with JavaScript disabled or failed — a plain, unmasked input that still submits.
Definition of done
8
Definition of done
8- The caret stays put during insertion, deletion, and mid-string editing.
- Pasted values are accepted with or without formatting.
- The server receives normalized values, never display strings.
- Screen readers announce the field's format once, not per separator.
- Autofill and mobile input produce correctly formatted values.
- Server-side validation exists independently of the mask.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Voice Dictation
Voice Dictation
Put a microphone in text fields so people can speak their input instead of typing it.
What it does
A dictation control on the app's longer text inputs that transcribes speech into the field as the user talks.
How it works
- 1 Add the control to the fields where typing is genuinely tedious: long descriptions, notes, comments, and message bodies. A microphone on a postcode field is clutter.
- 2 Show interim results in the field as they arrive, visually distinct from committed text, so the speaker can see it is working and correct course before they finish.
- 3 Reuse the app's existing Voice Transcription for the server-side path so one recognition configuration and one set of language settings serve both dictation and recorded audio.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/voice-dictation
Help Text Pattern
Help Text Pattern
Put field guidance in one predictable place, phrased the same way every time.
What it does
A consistent treatment for the short explanatory text that sits with a field and its control.
How it works
- 1 Collect the guidance the app currently scatters across placeholders, tooltips, asterisked footnotes, and modal help, and move it into one slot beneath the field.
- 2 Keep guidance that is required to complete the field permanently visible. A format rule hidden behind a hover target is not available to a touch user or a keyboard user.
- 3 Write help as the rule the user needs before typing — the accepted format, the consequence of the choice — not as a restatement of the label.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/help-text-pattern
Form Section Pattern
Form Section Pattern
Break long forms into labelled sections people can scan instead of read.
What it does
A section pattern grouping related fields under a heading, a description, and its own actions.
How it works
- 1 Find the forms that have grown past a screenful — settings, profiles, checkout, configuration — and group their fields by the question each group answers, not by the table the columns come from.
- 2 Give each section a heading in the document's heading order and an optional one-line description, so screen reader and keyboard users can jump between sections.
- 3 Allow at most one level of nesting. A section inside a section inside a tab gives the user no orientation and pushes the fields into a narrow gutter.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/form-section-pattern
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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2
Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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3
It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.