Fieldwork — Form Validation & Enhancement (Vanilla JS)

No — Fieldwork is completely dependency-free and written in vanilla JavaScript with ES modules, so it drops straight into any project with a plain script tag or module import and needs no build step. It works alongside any framework or none at all.

Fieldwork targets any modern browser that supports ES modules and standard DOM APIs (Chrome, Firefox, Safari, Edge). No polyfills or transpilation are required for evergreen browsers.

Accessibility is built in by default: Fieldwork automatically sets aria-invalid on invalid fields, links error messages via aria-describedby, uses role=alert for inline errors, and moves focus to the first invalid field on submit. You get correct ARIA wiring without writing a single accessibility attribute yourself.

Yes — Fieldwork supports fully custom rules alongside its 14 built-ins (required, email, match, minlength, and more). You can also supply per-field custom messages, so every error shown to users can match your product's tone and copy.

Yes — Fieldwork includes an optional async submit handler that posts your form data as JSON via fetch and surfaces server-returned errors inline using the setErrors() API. This means backend validation failures appear in the same accessible error UI as client-side ones.

The package includes the Fieldwork JS library, a single ready-to-use stylesheet, and a node:test + jsdom test suite so you can verify behaviour in your own environment. All visual styling is controlled via CSS custom properties (variables), making theming as simple as overriding a handful of values in your own CSS.