yaml-form

Generate a single self-contained HTML form from a YAML definition. The generated HTML inlines all CSS/JS, works offline (including file://), and handles rendering, required validation, conditional visibility, and submit actions entirely client-side — no server needed to host the form.

bunx @ncukondo/yaml-form generate form.yaml -o form.html
# or
npx @ncukondo/yaml-form generate form.yaml -o form.html

Install

• No install — bunx @ncukondo/yaml-form / npx @ncukondo/yaml-form

• Global — npm install -g @ncukondo/yaml-form (upgrade via npm)

• Single-file binary (linux/macOS x64 & arm64, windows x64; no runtime needed; upgrade later with yaml-form upgrade):

  # Linux / macOS
  curl -fsSL https://raw.githubusercontent.com/ncukondo/yaml-form-cli/main/install.sh | bash

  # Windows (PowerShell)
  irm https://raw.githubusercontent.com/ncukondo/yaml-form-cli/main/install.ps1 | iex

  The installer downloads the binary for your platform from GitHub Releases, verifies its SHA-256 checksum, and adds it to your PATH. Set YAML_FORM_VERSION=v0.x.x to pin a version or YAML_FORM_INSTALL_DIR to change the destination (default: ~/.local/bin, Windows: %LOCALAPPDATA%\yaml-form).

Usage

yaml-form generate <input.yaml|-> [-o <out.html>] [--json]
yaml-form validate <input.yaml|-> [--json]
yaml-form eval <input.yaml|-> --answers <json|@file|->
yaml-form schema
yaml-form docs [<topic>]
yaml-form example [<name>]
yaml-form upgrade [--dry-run]

• generate writes the HTML form (stdout by default, -o to a file).
• validate parses and cross-checks only, reporting every problem at once.
• eval prints each item's visible_when result for a set of answers, computed by the same code the generated form runs — a browser-free way to test conditional visibility.
• schema / docs / example print the format's JSON Schema, field reference, and a runnable sample; they work offline so an npx or binary install is self-documenting.
• Input - reads YAML from stdin; --json makes a command emit a single {"ok":...} object. Exit codes: 0 success, 1 operation failed, 2 usage error. See yaml-form --help for the full contract.

YAML definition

# yaml-language-server: $schema=https://raw.githubusercontent.com/ncukondo/yaml-form-cli/main/schema/yaml-form.schema.json
title: "Session feedback"
actions:
  - type: post
    url: "https://example.com/api/submit"
post_submit:
  message: "Thank you!"
items:
  - type: short_text
    id: name
    title: "Your name"
    required: true

  - type: choice
    id: role
    title: "Your role"
    choices: [student, resident, faculty]

  - type: rubric
    id: talk_rubric
    title: "Rate the talk"
    choices:
      - { title: "Novice", value: "1" }
      - { title: "Expert", value: "2" }
    items:
      - id: clarity
        title: "Clarity"
        descriptors: ["Hard to follow", "Consistently clear"]

  - type: long_text
    id: clarity_advice
    title: "How could clarity improve?"
    visible_when: 'talk_rubric.clarity = "1"'

Item types: constant, short_text, long_text, choice, choice_table (questions as rows sharing one scale), rubric (a choice_table with per-cell descriptor text). Conditional visibility uses @ncukondo/dynamic-form-rules expressions; rule keys are validated at generation time, so typos fail fast. Submit actions: log (console), post (JSON POST), mailto.

Opening a form with query parameters prefills matching fields (form.html?name=John&tags=a,b). A constant item with from_url: true (optionally hidden: true) turns that into per-respondent distribution URLs whose identifier lands in the submit payload — if such URLs identify respondents, disclose it to them.

Answers are autosaved to the browser's localStorage and restored when the same URL is reopened (announced, discardable); a successful submit clears the draft. Opt out with autosave: false — recommended for shared or kiosk devices.

Full reference: docs/reference.md — every field, answer shapes, the submit payload, and rule syntax. Complete example: examples/sample.yaml. A JSON Schema (schema/yaml-form.schema.json) provides editor completion/validation via yaml-language-server.

Development

Toolchain: Bun + TypeScript.

bun install
bun run check   # typecheck + lint + tests

Process: TDD per task file in tasks/; decisions are recorded in decisions/; parallel-safe tasks are developed in separate git worktrees. See decisions/0009-development-process.md.

Releases: pushing a tag vX.Y.Z (matching package.json) builds per-platform binaries, creates a GitHub release, and publishes to npm.

Related projects

• flexible-form — Next.js form builder this YAML schema originates from
• @ncukondo/dynamic-form-rules — rule engine used for visible_when

License

MIT