thedaviddias/form-validation

Form Validation

Validate and provide feedback

What it solves

A Form Validation pattern helps teams create a reliable way to provide field-level and form-level feedback without interrupting users before they have enough information to succeed. It is most useful when teams need account creation. Compared with adjacent patterns, this pattern should reduce friction without hiding the state, rules, or recovery paths people need to keep moving.

When to use

• Account creation
• Checkout and billing forms
• Workflow forms with both client and server rules

When to avoid

• Use a simpler native control when the value is binary, tiny, or fully constrained.
• Avoid custom behavior when a native browser input already solves the main job well.
• Do not add extra formatting or validation if the product does not benefit from it.

Implementation workflow

1. Confirm the pattern matches the problem and constraints before copying the example.
2. Start from the anatomy and examples in references/pattern.md, then choose the smallest viable variation.
3. Apply accessibility, performance, and interaction guardrails before layering visual polish.
4. Use the testing guidance to verify behavior across keyboard, screen reader, responsive, and failure scenarios.

Accessibility guardrails

Keyboard Interaction

• [ ] Verify that form validation can be completed using keyboard alone.
• [ ] Keep focus order logical when the pattern opens, updates, or reveals additional UI.
• [ ] Preserve a visible focus state that is still readable at high zoom.

Screen Reader Support

• [ ] Use semantic elements first, then add ARIA only where semantics alone are not enough.
• [ ] Announce state changes such as errors, loading, or completion in the right place and with the right politeness.
• [ ] Connect labels, hints, and status text with aria-describedby or structural headings when useful.

Visual Accessibility

• [ ] Do not rely on color alone to convey severity, completion, or selection state.

Common mistakes

Using the wrong validation moment

The Problem: Immediate validation on partial input makes the pattern feel punitive and noisy.

How to Fix It? Wait until the user has enough information in the field, then validate on blur, pause, or submit depending on the risk of the rule.

Separating labels, hints, and errors

The Problem: People cannot tell which message belongs to which control when the copy is visually detached.

How to Fix It? Keep labels, helper text, and validation messages tightly grouped and connected with aria-describedby where appropriate.

Forgetting touch and autofill behavior

The Problem: Desktop-only styling hides the fact that mobile keyboards, autofill, and paste flows behave differently.

How to Fix It? Test the control with autofill, paste, zoom, and on-screen keyboards before calling the pattern complete.

Related patterns

• https://uxpatterns.dev/patterns/forms/button
• https://uxpatterns.dev/patterns/forms/date-input
• https://uxpatterns.dev/patterns/forms/text-field

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For full implementation detail, examples, and testing notes, see references/pattern.md.

Pattern page: https://uxpatterns.dev/patterns/forms/form-validation