@tempots/eslint-plugin

ESLint plugin for TempoTS to help catch common signal usage issues and prevent memory leaks.

Installation

npm install -D @tempots/eslint-plugin

Quick Setup

Use the recommended configuration:

// eslint.config.js
import tempots from '@tempots/eslint-plugin'

export default [
  tempots.configs.recommended,
  // ... your other configs
]

This enables all rules with sensible defaults. For maximum safety, use tempots.configs.strict instead (all rules set to error).

Rules

Signal Lifecycle

• no-module-level-signals (warn) - Warns about signals created at module level outside renderables. Use untracked() for intentionally long-lived signals.
• require-untracked-disposal (error) - Requires disposal of signals created with untracked() to prevent memory leaks.
• require-async-signal-disposal (warn) - Requires proper disposal for signals created in async contexts (setTimeout, Promise callbacks) where auto-disposal doesn't apply.
• no-unnecessary-disposal (warn) - Warns about redundant manual disposal of auto-disposed signals. Auto-fixable.
• no-signal-reassignment (error) - Prevents reassignment of signal variables, which would leak the original signal.
• prefer-const-signals (warn) - Prefers const for signal declarations to prevent accidental reassignment. Auto-fixable.

Renderable Patterns

• no-renderable-signal-map (warn) - Warns when mapping signals to renderables (e.g., signal.map(v => html.div(v))). Signals can be passed directly into renderables.
• no-empty-fragment (warn) - Warns about Fragment() with no children. Use Empty instead.
• no-single-child-fragment (warn) - Warns about Fragment() with a single child, which is unnecessary wrapping.

Examples

Correct signal usage

const MyComponent = ctx => {
  const count = prop(0)          // Auto-disposed
  const doubled = count.map(x => x * 2) // Auto-disposed

  return html.div(count, ' x 2 = ', doubled)
}

Async signals need manual tracking

const MyComponent = ctx => {
  const data = prop(null)        // Create synchronously (auto-disposed)

  setTimeout(() => {
    data.set(fetchedValue)       // Just update the value
  }, 1000)

  return html.div(data)
}

Module-level signals need untracked

const globalCount = untracked(() => prop(0))
// Remember to dispose when done: globalCount.dispose()

Custom Configuration

// eslint.config.js
import tempots from '@tempots/eslint-plugin'

export default [
  {
    plugins: { tempots },
    rules: {
      'tempots/no-module-level-signals': 'warn',
      'tempots/require-untracked-disposal': 'error',
      'tempots/no-signal-reassignment': 'error',
      'tempots/prefer-const-signals': 'warn',
    },
  },
]

For more information, see the Tempo documentation.