Build Validate
Validate code components before deployment to catch issues early.
When to Use This Skill
Use when:
- User is about to deploy and wants to check for issues first
- Proactively before running
webflow library share - User asks to validate, check, or verify their components
- After making significant changes to components
Do NOT use when:
- Deployment already failed (use troubleshoot-deploy instead)
- Just building for local development
- Auditing code quality (use component-audit instead)
Instructions
Phase 1: Project Structure Check
- Verify webflow.json exists:
- Check for required fields (library.name, library.components) - Validate glob pattern matches component files — the recommended pattern is "./src/**/*.webflow.@(js|jsx|mjs|ts|tsx)" covering all supported extensions - Check globals path if specified — file must exist and be importable - Check bundleConfig path if specified — file must exist
- Check dependencies:
- Verify @webflow/webflow-cli installed - Verify @webflow/data-types installed - Verify @webflow/react installed - Check for version compatibility (check installed versions, don't assume specific versions)
- Verify component files:
- Find all .webflow.tsx / .webflow.ts files matching the glob pattern - Ensure matching React components exist - Check for orphaned definition files
- Validate imports in
.webflow.tsxfiles:
- Must import declareComponent from @webflow/react - Must import props from @webflow/data-types (if props are defined) - Must import the actual React component being declared
Phase 2: Component Analysis
- For each component, check:
- declareComponent is called with the component and a config object - name is provided in the config - All props have name properties and appropriate defaultValue where applicable - Prop types are valid — the 11 supported types are: - Text (alias: String) — single line text input - RichText — multi-line text with formatting - TextNode — single/multi-line text editable on canvas - Link — URL input (returns {href, target, preload} object) - Image — image upload and selection - Number — numeric input - Boolean — true/false toggle - Variant — dropdown with predefined options (requires options array) - Visibility — show/hide controls - Slot — content areas for child components - ID — HTML element ID
- Validate component options:
- If options object is present, validate: - applyTagSelectors is a boolean (default: false) — enables site tag selectors in Shadow DOM - ssr is a boolean (default: true) — controls server-side rendering
- Check for SSR issues:
- Scan for browser-only API usage outside of useEffect or guarded blocks: - window, document, localStorage, sessionStorage, navigator - Flag dynamic/personalized content patterns (user-specific dashboards, authenticated views) - Flag heavy/interactive UI that doesn't benefit from SSR (charts, 3D scenes, maps, animation-heavy elements) - Flag non-deterministic output (random numbers, time-based values that differ server vs client) - Suggest ssr: false in options if component is purely interactive or browser-dependent
- Check styling:
- Verify styles are imported in .webflow.tsx or via globals file - Check for site class usage — site classes do NOT work in Shadow DOM - Site variables DO work: var(--variable-name, fallback) - Inherited CSS properties DO work: font-family: inherit - Tag selectors work IF applyTagSelectors: true is set in component options - Validate CSS-in-JS setup if used (see CSS-in-JS detection below)
- Check for Shadow DOM + React Context issues:
- If a component uses slots (props.Slot) AND imports/uses useContext or a Context Provider: - Warn that parent and child components in slots cannot share React Context — each child renders in its own Shadow DOM with a separate React root - Suggest alternatives: Nano Stores, custom events, URL parameters, or browser storage
Phase 3: Build Test
- Run TypeScript/build check:
- Check for TypeScript compilation errors - Verify all imports resolve correctly - Identify any build-time issues
- Check bundle size:
- If a build output exists, verify total bundle size is under 50MB (maximum bundle limit) - If over limit, flag as error and suggest optimization
- Run local bundle test (optional, suggest to user):
- Suggest running npx webflow library bundle --public-path http://localhost:4000/ to test bundling before sharing - If bundling issues occur, suggest --debug-bundler flag to inspect the final webpack config
Phase 4: Detect Framework-Specific Setup
- CSS-in-JS library detection:
- If project uses styled-components: verify @webflow/styled-components-utils is installed and styledComponentsShadowDomDecorator is exported from globals decorators array - If project uses Emotion or Material UI (@emotion/styled, @emotion/react, @mui/material): verify @webflow/emotion-utils is installed and emotionShadowDomDecorator is exported from globals decorators array
- Tailwind CSS detection:
- If project uses Tailwind CSS (tailwindcss in dependencies): - Verify @tailwindcss/postcss is installed - Verify postcss.config.mjs exists with @tailwindcss/postcss plugin - Verify Tailwind CSS is imported in globals file (e.g., @import "tailwindcss" in globals.css)
- Sass/Less preprocessor detection:
- If project uses Sass (.scss files or sass in dependencies): verify sass and sass-loader are installed, and a webpack config adds the .scss rule - If project uses Less (.less files or less in dependencies): verify less and less-loader are installed, and a webpack config adds the .less rule - For either: verify bundleConfig is set in webflow.json pointing to the webpack config
- Webpack custom config validation (if
bundleConfigis specified):
- Verify the file exists at the specified path - Verify it uses CommonJS exports (module.exports) - Warn if it attempts to override blocked properties: entry, output, target (these are silently filtered out) - Verify module.rules uses function syntax (currentRules) => {...}, not an array
Phase 5: Report Results
- Generate validation report:
- List all checks performed - Show passed/failed/warning status - Provide fix suggestions for failures - Indicate deployment readiness
Validation Checks
Required Checks
| Check | Severity | Description |
|---|---|---|
| webflow.json exists | Error | Required for CLI |
| Dependencies installed | Error | @webflow/webflow-cli, @webflow/data-types, @webflow/react |
| Component files exist | Error | React + definition files present |
| declareComponent called | Error | Required in.webflow.tsx with correct imports |
| Valid prop types | Error | Only the 11 supported types (Text/String, RichText, TextNode, Link, Image, Number, Boolean, Variant, Visibility, Slot, ID) |
| Build succeeds | Error | No compilation errors |
| Bundle size < 50MB | Error | Maximum bundle limit enforced by Webflow |
Warning Checks
| Check | Severity | Description |
|---|---|---|
| Props have defaults | Warning | Better designer experience |
| SSR compatibility | Warning | Browser APIs, dynamic content, heavy UI, non-deterministic output |
| Styles imported | Warning | Styles may not appear in Shadow DOM |
| Site class usage | Warning | Site classes don't work in Shadow DOM — use component-specific classes |
| Shadow DOM + Context | Warning | Slots prevent React Context sharing between parent/child |
| CSS-in-JS decorator | Warning | styled-components/Emotion need Shadow DOM decorators |
| Tailwind setup | Warning | Missing postcss config or globals import |
| Sass/Less setup | Warning | Missing loaders or webpack config |
| Webpack blocked props | Warning | entry, output, target overrides are silently ignored |
| Webpack rules format | Warning | Must use function syntax, not array |
| Component options | Warning | applyTagSelectors and ssr must be booleans |
| Glob pattern coverage | Warning | Pattern should cover all supported extensions (.js,.jsx,.mjs,.ts,.tsx) |
| bundleConfig file | Warning | File must exist if specified in webflow.json |
Info Checks
| Check | Severity | Description |
|---|---|---|
| Component count | Info | Number of components |
| Prop count | Info | Props per component |
| Bundle size | Info | Current bundle size vs 50MB limit |
| Frameworks detected | Info | CSS-in-JS, Tailwind, Sass/Less usage |
Examples
User prompt:
Check if my components are ready to deployResponse:
🔍 Build Validation: My Component Library
Running pre-deployment checks...
---
## Project Structure
✅ webflow.json found
✅ library.name: "My Component Library"
✅ library.components: "./src/**/*.webflow.@(js|jsx|mjs|ts|tsx)"
✅ globals: "./src/globals.ts"
✅ bundleConfig: not specified (using defaults)
---
## Dependencies
✅ @webflow/webflow-cli: installed
✅ @webflow/data-types: installed
✅ @webflow/react: installed
✅ react: installed
✅ typescript: installed
---
## Frameworks Detected
✅ Tailwind CSS detected
✅ @tailwindcss/postcss installed
✅ postcss.config.mjs found
✅ globals.css imports Tailwind
---
## Components Found (4)
### 1. Button ✅
- File: src/components/Button/Button.webflow.tsx
- Imports: ✅ declareComponent, ✅ props, ✅ Button component
- Props: label (Text), variant (Variant), disabled (Boolean)
- All props have defaults ✅
- SSR compatible ✅
- Options: applyTagSelectors: true ✅
- Styles imported ✅
### 2. Card ✅
- File: src/components/Card/Card.webflow.tsx
- Imports: ✅ declareComponent, ✅ props, ✅ Card component
- Props: title (Text), image (Image), content (RichText), link (Link)
- All props have defaults ✅
- SSR compatible ✅
- Styles imported ✅
### 3. Modal ⚠️
- File: src/components/Modal/Modal.webflow.tsx
- Imports: ✅ declareComponent, ✅ props, ✅ Modal component
- Props: title (Text), isOpen (Boolean), content (Slot)
- All props have defaults ✅
- ⚠️ SSR Issue: Uses `document.body` in render
→ Suggestion: Add `ssr: false` to options or wrap in useEffect
- Styles imported ✅
### 4. CartIcon ⚠️
- File: src/components/CartIcon/CartIcon.webflow.tsx
- Imports: ✅ declareComponent, ✅ CartIcon component
- Props: none
- ⚠️ Missing props - component has no editable properties
→ Suggestion: Consider adding props for designer customization
- ⚠️ Uses localStorage without SSR guard
→ Suggestion: Wrap in useEffect or useState initializer
- Styles imported ✅
---
## Build Test
✅ Build completed successfully
✅ No TypeScript errors
✅ No webpack errors
✅ Bundle size: 2.3MB / 50MB limit
---
## Summary
| Category | Status |
|----------|--------|
| Project Structure | ✅ Pass |
| Dependencies | ✅ Pass |
| Frameworks | ✅ Pass |
| Components | ⚠️ 2 warnings |
| Build | ✅ Pass |
---
## Ready to Deploy: ⚠️ WITH WARNINGS
You can deploy, but consider fixing these issues:
1. **Modal SSR Issue**
Add to Modal.webflow.tsx:options: { ssr: false }
1. **CartIcon localStorage Usage** Update CartIcon.tsx: `const [count, setCount] = useState(() => {if (typeof window === "undefined") return 0; return parseInt(localStorage.getItem("cartCount") || "0");});`
---
💡 To deploy: `npx webflow library share` 💡 To test locally first: `npx webflow library bundle --public-path http://localhost:4000/`
Example: Build Failure
🔍 Build Validation: My Component Library
Running pre-deployment checks...
---
## Project Structure
✅ webflow.json found ⚠️ library.components uses narrow glob: "./src/**/*.webflow.tsx" → Recommendation: Use "./src/**/*.webflow.@(js|jsx|mjs|ts|tsx)" to cover all supported extensions
---
## Dependencies
❌ Missing: @webflow/react Fix: npm install --save-dev @webflow/react
---
## Build Test
❌ Build Failed
Error in src/components/Button/Button.webflow.tsx:
Module not found: Error: Can't resolve '@webflow/react'
---
## Summary
| Category | Status |
| --- | --- |
| Dependencies | ❌ 1 error |
| Build | ❌ Failed |
---
## Ready to Deploy: ❌ NO
Fix the following before deployment:
1. **Install missing dependency** `npm install --save-dev @webflow/react`
2. **Re-run validation** After installing, run this check again.
Example: CSS-in-JS Missing Decorator
🔍 Build Validation: My Component Library
---
## Frameworks Detected
⚠️ styled-components detected but Shadow DOM decorator not configured → Install: npm install @webflow/styled-components-utils → Add to globals.ts: `typescript import {styledComponentsShadowDomDecorator} from "@webflow/styled-components-utils"; export const decorators = [styledComponentsShadowDomDecorator];` → Reference globals in webflow.json: `json {"library": {"globals": "./src/globals.ts"}}`
Without this, styled-components styles will be injected into document.head instead of the Shadow DOM, and your components will appear unstyled.
Example: Webpack Config Issues
🔍 Build Validation: My Component Library
---
## Webpack Configuration
⚠️ webpack.webflow.js: `module.rules` uses array syntax → Must use function syntax: `rules: (currentRules) => {return [...];}` → Array syntax will not work — the function receives current rules to extend
⚠️ webpack.webflow.js: overrides `output` property → The `output` property is blocked and will be silently ignored → Blocked properties: entry, output, target
💡 Use `--debug-bundler` flag to inspect the final merged webpack config: npx webflow library bundle --debug-bundler
Example: Shadow DOM Context Warning
## Components Found (2)
### 1. ThemeProvider ⚠️
- File: src/components/ThemeProvider/ThemeProvider.webflow.tsx
- Props: theme (Variant), children (Slot)
- ⚠️ Shadow DOM + React Context Issue: Component uses Slot prop AND React Context (ThemeContext). Children placed in slots render in separate Shadow DOM containers with their own React roots — they cannot access this Context. Alternatives for cross-component state:
- Nano Stores (lightweight reactive state)
- Custom events (window.dispatchEvent/addEventListener)
- URL parameters (for shareable state)
- Browser storage (localStorage/sessionStorage)
Guidelines
Validation Order
Run checks in this order for efficiency:
- Project structure (fast, catches obvious issues)
- Dependencies (medium, required for build)
- Component analysis (medium, catches code issues)
- Framework detection (medium, validates CSS-in-JS/Tailwind/Sass setup)
- Build test (slow, but required)
SSR Detection Patterns
Look for these patterns that indicate SSR issues:
// Direct browser API usage (will break SSR)
window.innerWidth
document.getElementById
localStorage.getItem
navigator.userAgent
sessionStorage.getItem
// Dynamic/personalized content (may cause hydration mismatch)
// User-specific dashboards, authenticated views
// Heavy/interactive UI (SSR adds no value, re-renders anyway)
// Charts, 3D scenes, maps, animation-driven elements
// Non-deterministic output (differs server vs client)
Math.random()
new Date().toLocaleString()
// Safe patterns (in useEffect or state initializer)
useEffect(() => {
// Browser APIs here are fine
}, []);
useState(() => {
if (typeof window === "undefined") return default;
return window.innerWidth;
});When SSR issues are found, prominently suggest the ssr: false option:
export default declareComponent(MyComponent, {
name: "My Component",
options: {
ssr: false // Disables server-side rendering
},
});CSS-in-JS / Tailwind / Preprocessor Detection
Check project dependencies and files to detect styling frameworks:
styled-components:
- Detect:
styled-componentsin package.json dependencies - Require:
@webflow/styled-components-utilsinstalled - Require:
styledComponentsShadowDomDecoratorin globals decorators array
Emotion / Material UI:
- Detect:
@emotion/styled,@emotion/react, or@mui/materialin dependencies - Require:
@webflow/emotion-utilsinstalled - Require:
emotionShadowDomDecoratorin globals decorators array
Tailwind CSS:
- Detect:
tailwindcssin dependencies - Require:
@tailwindcss/postcssinstalled - Require:
postcss.config.mjswith@tailwindcss/postcssplugin - Require: Tailwind import in globals CSS (
@import "tailwindcss")
Sass:
- Detect:
.scssfiles in src orsassin dependencies - Require:
sassandsass-loaderinstalled as dev dependencies - Require: webpack config with
.scssrule using function syntax for module.rules - Require:
bundleConfigset in webflow.json
Less:
- Detect:
.lessfiles in src orlessin dependencies - Require:
lessandless-loaderinstalled as dev dependencies - Require: webpack config with
.lessrule using function syntax for module.rules - Require:
bundleConfigset in webflow.json
Webpack Config Validation Rules
When bundleConfig is specified in webflow.json:
- File must exist at the specified path
- Must use CommonJS:
module.exports = {...} - Blocked properties that are silently ignored:
entry,output,target module.rulesmust be a function, not an array:rules: (currentRules) => {...}ModuleFederationPluginandMiniCssExtractPluginare auto-deduplicated
Common Build Errors
| Error | Cause | Fix |
|---|---|---|
| "Can't resolve '@webflow/react'" | Missing dependency | npm i -D @webflow/react |
| "Cannot find module './Component'" | Wrong import path | Check relative paths |
| "Type 'X' is not assignable" | TypeScript error | Fix type mismatch |
| "Unexpected token" | Syntax error | Check JSX/TS syntax |
| "Maximum call stack" | Circular import | Break dependency cycle |
| Bundle exceeds 50MB | Too many/large dependencies | Tree-shake, lazy load, replace heavy libs |
| Styles not appearing | Missing Shadow DOM decorator | Add CSS-in-JS decorator or import styles in.webflow.tsx |
Bundle Size Optimization
Quick wins for reducing bundle size:
- Use production build: Ensure minification is enabled
- Tree-shake imports: Import specific exports
- Replace heavy libraries: moment → date-fns, lodash → lodash-es
- Lazy load: Dynamic imports for heavy components
- Check for duplicates: Multiple React versions, etc.
- Monitor size: Bundle must stay under 50MB limit