# solidjs

A Cursor rule for SolidJS 1.x covering reactivity, component structure, state, effects, and cleanup in JavaScript and JSX files.

- rule · `type=rule` · Cursor · ★ 3580
- Author: sanjeed5
- License: CC0-1.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/solidjs.mdc
- Updated: 2026-05-19
- HTML: https://affpapa.org/en/nevibecode/rules/solidjs

## What it does

This rule guides SolidJS 1.x work in files matching `**/*.{js,jsx}`. It keeps component props reactive by avoiding top-level destructuring, using `mergeProps` for defaults, and applying `splitProps` when known and rest props must be separated. Local primitive state uses `createSignal`; nested or shared objects use `createStore`.

The guidance puts side effects inside `createEffect` and resource disposal inside `onCleanup`, including timers, subscriptions, and event listeners. It also recommends small components, PascalCase filenames, and Vite CSS Modules for local styles. The scope is SolidJS 1.x: SolidJS 2.0 is described as experimental, so this rule should not be used as guidance for its APIs.

## Install

### Cursor (native platform)

**Manually: put the files in place**
- File: `.cursor/rules/solidjs.mdc` — Frontmatter: description, globs, alwaysApply

### Claude Code

**Manually: put the files in place**
- File: `.claude/rules/solidjs.md` — The paths frontmatter field limits the files: move globs from the source into paths

### Codex

**AGENTS.md**
- Codex reads AGENTS.md: paste the rule text there

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/instructions/solidjs.instructions.md` — The applyTo field sets which files it applies to: move globs from the source into applyTo

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/rules/solidjs.md`

### Cline

**Manually: put the files in place**
- File: `.clinerules/solidjs.md`

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/solidjs.mdc

## When to use it
- preserve reactive component props
- choose state primitives for local and nested data
- place side effects inside `createEffect`
- dispose of timers and subscriptions with `onCleanup`
- separate declared and pass-through props with `splitProps`

## Example prompts
- Review this SolidJS component and remove top-level props destructuring.
- Use `createSignal` for local state and `createStore` for nested data.
- Find side effects in `*.jsx` files and add cleanup with `onCleanup`.

## Source text · solidjs.mdc · CC0-1.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 2f83f2e777f036f8.

BEGIN THIRD-PARTY FILE 2f83f2e777f036f8
````text
---
description: This guide provides definitive, opinionated best practices for writing high-performance, maintainable SolidJS applications, focusing on reactivity, component architecture, and common pitfalls.
globs: **/*.{js,jsx}
---
# solidjs Best Practices

This document outlines the definitive best practices for developing with SolidJS 1.x. Adhere to these guidelines to leverage Solid's fine-grained reactivity, ensure optimal performance, and maintain a consistent, scalable codebase.

---

## 1. Use SolidJS 1.x (Stable)

**Always use the current stable 1.x release.** SolidJS 2.0 is experimental and not ready for production. Avoid any features or APIs mentioned for 2.0.

## 2. Component Architecture & Code Organization

### 2.1. Component File Naming

**Use PascalCase for component filenames.** This clearly distinguishes components from other modules.

*   ❌ BAD: `mybutton.jsx`, `user-profile.jsx`
*   ✅ GOOD: `MyButton.jsx`, `UserProfile.jsx`

### 2.2. Keep Components Lean

**Components should be small and focused.** Extract complex logic or UI parts into separate components or custom primitives.

### 2.3. Colocate Styles

**Use Vite's CSS Modules for component-specific styling.** This provides scoped styles without runtime overhead.

*   ❌ BAD: Global CSS files, CSS-in-JS libraries with runtime.
*   ✅ GOOD:
    ```jsx
    // MyComponent.module.css
    .container {
      background-color: var(--color-primary);
    }
    .text {
      color: white;
    }

    // MyComponent.jsx
    import styles from './MyComponent.module.css';

    function MyComponent() {
      return <div class={styles.container}><span class={styles.text}>Hello</span></div>;
    }
    ```

## 3. Props Handling

SolidJS props are reactive getters. Incorrect handling breaks reactivity.

### 3.1. Never Destructure Props Directly

**Do not destructure `props` at the component's top level.** This immediately loses reactivity. Access props via `props.propertyName`.

*   ❌ BAD:
    ```jsx
    function MyComponent({ name, age }) { // React pattern, breaks Solid reactivity
      return <div>{name} is {age}</div>;
    }
    ```
*   ✅ GOOD:
    ```jsx
    function MyComponent(props) {
      return <div>{props.name} is {props.age}</div>; // Access directly
    }
    ```

### 3.2. Apply Default Props with `mergeProps`

**Use `mergeProps` for default props.** This preserves reactivity and merges objects non-destructively.

*   ❌ BAD:
    ```jsx
    function MyComponent(props) {
      const name = props.name || "Guest"; // Loses reactivity if props.name is a signal
      return <div>Hello, {name}</div>;
    }
    ```
*   ✅ GOOD:
    ```jsx
    import { mergeProps } from 'solid-js';

    function MyComponent(props) {
      const merged = mergeProps({ name: "Guest", greeting: "Hello" }, props);
      return <div>{merged.greeting}, {merged.name}!</div>;
    }
    ```

### 3.3. Use `splitProps` for Spreading

**When spreading props, use `splitProps` to separate known props from rest props.** This is crucial for accessibility and avoiding prop conflicts.

*   ❌ BAD:
    ```jsx
    function MyInput(props) {
      return <input type="text" {...props} />; // Unsafe, can overwrite internal props
    }
    ```
*   ✅ GOOD:
    ```jsx
    import { splitProps } from 'solid-js';

    function MyInput(props) {
      const [local, rest] = splitProps(props, ["label", "onChange"]);
      return (
        <label>
          {local.label}
          <input type="text" onChange={local.onChange} {...rest} />
        </label>
      );
    }
    ```

## 4. State Management

### 4.1. Signals for Local State

**Use `createSignal` for simple, primitive, or local component state.** It's the most performant and idiomatic way to manage reactive values.

*   ❌ BAD: `let count = 0;` (non-reactive)
*   ✅ GOOD:
    ```jsx
    import { createSignal } from 'solid-js';

    function Counter() {
      const [count, setCount] = createSignal(0);
      return <button onClick={() => setCount(c => c + 1)}>{count()}</button>;
    }
    ```
````
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