PropDiff

Before you change a component's props, see every call site and exactly which props each one passes -> so a prop rename, removal, or type change never silently breaks half the app.

PropDiff scans your workspace for every usage of a React (JSX/TSX), Vue SFC, or Svelte component, parses the actual props passed at each site, compares them against the component's declared props, and turns the result into a clickable report.

Features

Usage finder

• Finds every <ComponentName ...> tag across the workspace, including multi-line tags and self-closing tags
• Parses each usage site into prop name, raw value text, and a value kind:
  • string literal (variant="primary")
  • number (size={2})
  • boolean shorthand (disabled)
  • expression (variant={dynamicVariant})
  • spread ({...rest})
  • event handler (onClick={save}, @close="onClose", on:click={handle})
• Vue support: scans only the <template> section and matches both PascalCase and kebab-case tags, including :prop bindings and @event handlers
• Svelte support: on: handlers, {value} shorthand, and {...spread}
• Respects the propDiff.excludeGlobs setting (node_modules, dist, build, and similar are excluded by default)

Component definition analysis

Locates the component's own definition and parses its declared props, best-effort, from:

• TypeScript: props interface/type or destructured props parameter (defaults detected from = value)
• PropTypes: Component.propTypes plus Component.defaultProps
• Vue: defineProps<{...}>(), defineProps({...}), options API props: {...} or props: [...]
• Svelte: export let name (with or without a default)

Analysis and warnings

• Prop usage matrix: for each prop, how many sites pass it, like variant -> 12/15 usages
• Per-site warnings:
  • Unknown prop: passed at a site but not in the declared prop set
  • Missing prop: declared without a default and passed at most other sites, but absent here
  • Inconsistent value kind: the same prop is passed as a string at some sites and as a number or expression at others

Report panel

The PropDiff activity bar view shows:

• Summary header: component name, clickable definition location, total usages, files, warnings, and scan time
• Declared props with required/optional/default markers
• The prop usage matrix as frequency chips
• Per-file groups listing every usage with its props, value kinds, and warnings
• Every row is clickable -> jumps to that exact usage location
• Refresh button re-runs the analysis
• Copy report button puts a markdown report (matrix table plus per-usage table) on the clipboard

CodeLens

Exported PascalCase components in JSX/TSX files, and Vue/Svelte single-file components, get a CodeLens above the definition:

5 usages -> PropDiff

Click it to analyze that component immediately.

Status bar

While a report is open, the status bar shows PropDiff: <Component> | N usages; click it to focus the report panel.

Commands

Usage

1. Open a JSX/TSX, Vue, or Svelte file and place the cursor on a component name
2. Run PropDiff: Analyze Component (command palette or editor context menu), or click the N usages -> PropDiff CodeLens above a component definition
3. Read the report in the PropDiff panel: matrix, per-file usages, warnings
4. Click any usage row to jump to it; use Copy Report as Markdown to share the findings in a PR

A walkthrough is available under Help -> Get Started -> Get Started with PropDiff.

Example

Component definition in Button.tsx:

interface ButtonProps {
  variant: 'primary' | 'secondary';
  size?: number;
  onClick?: () => void;
}
export function Button({ variant, size = 2, onClick }: ButtonProps) {
  return <button className={variant}>...</button>;
}

PropDiff report:

<Button>  Definition: src/Button.tsx:6 (typescript)
15 usages | 6 files | 2 warnings

variant -> 14/15    size -> 9/15    onClick -> 12/15

src/pages/Dashboard.tsx
  :42  <Button variant="primary" onClick={onSave} />
  :77  <Button size={3} />
       Missing prop "variant" -> declared without a default and passed at 14/15 sites
src/legacy/Toolbar.tsx
  :12  <Button variant={2} color="red" />
       Inconsistent value kind for "variant" -> number here, usually string
       Unknown prop "color" -> not in the declared props of Button

Configuration

{
  "propDiff.excludeGlobs": [
    "**/node_modules/**",
    "**/dist/**",
    "**/build/**",
    "**/out/**",
    "**/.next/**",
    "**/coverage/**"
  ],
  "propDiff.maxResults": 500
}

Supported frameworks

• React (JSX/TSX)
• Vue 2/3 single-file components
• Svelte

Requirements

• VS Code 1.85.0 or higher

Author

Kanaihya Kumar -> kanaihyakmr@gmail.com

License

MIT