---
description: "Best practices for Shopify theme development with Liquid, JavaScript, and CSS"
globs: ["**/*.liquid", "assets/**/*.js", "assets/**/*.css", "sections/**/*.liquid", "snippets/**/*.liquid", "templates/**/*.liquid"]
alwaysApply: false
---
# Shopify Theme Development Best Practices

## Project Structure
- Adopt a clear **directory structure**, e.g., `sections`, `snippets`, `templates`, `assets`.
- Organize **generic modules** (like JavaScript functionalities) into separate files.
- Keep **Liquid files** concise and focused on single responsibilities, avoiding monolithic files.
- Organize templates and sections by **page or functionality**.
- Implement proper **internationalization (i18n)** file management.
- Utilize **SCSS/CSS Modules** for style organization to prevent global pollution.

## Liquid Templating
- Prefer the `render` tag over `include`.
- Limit **database queries** within loops to avoid N+1 issues.
- Use **filters** judiciously, especially complex computational ones.
- Leverage Liquid's **caching mechanisms** to reduce redundant calculations.
- Avoid complex **logic handling** directly in Liquid; move intricate logic to JavaScript.
- Use `assign` and `capture` to define and reuse variables effectively.

## JavaScript Development
- Modularize JS, using **ES Modules** for imports and exports.
- Follow modern JavaScript **best practices**, such as `const`/`let`, arrow functions, etc.
- Avoid direct **DOM manipulation**; prioritize event delegation.
- Optimize **JavaScript performance** to reduce repaints and reflows.
- Consider using **Webpack/Rollup** for bundling and code optimization.
- Write clear **comments** and **JSDoc**.

## CSS/SCSS Styling
- Adhere to naming conventions like **BEM, OOCSS, or Utility-First CSS**.
- Optimize **CSS selectors** to improve rendering performance.
- Use **CSS variables** to manage theme configurations like colors and fonts.
- Implement **responsive design** to ensure consistent theme appearance across devices.
- Minimize **CSS file size** by removing unused styles.
- Make good use of **SCSS mixins** and **functions**.

## Sections and Blocks
- Utilize Section **Schema** to define configurable options.
- Maintain **section independence and reusability**.
- Provide clear **presets** for sections.
- Use **Blocks** appropriately to enhance section flexibility.
- Ensure sections provide a good user experience in the **Shopify Customizer**.
- Avoid hardcoding content within sections; use Schema configurations whenever possible.

## Performance Optimization
- Optimize **image loading** by using Shopify's CDN and the `image_url` filter.
- Minify **JavaScript and CSS files**.
- Leverage **browser caching**.
- Reduce the number of **HTTP requests**.
- Consider **lazy loading**.
- Monitor **theme performance** using Google Lighthouse and Shopify Theme Check.

## Accessibility (A11y)
- Ensure all interactive elements are **keyboard accessible**.
- Provide meaningful **`alt` text** for images.
- Use correct **HTML semantic tags**.
- Consider **color contrast**.
- Implement clear **focus states**.
- Use **ARIA attributes** to enhance the accessibility of complex components.

## Maintenance and Scalability
- Write clear **code comments** and documentation.
- Follow **naming conventions** to maintain code consistency.
- Regularly **test** theme functionalities.
- Ensure compatibility across different **browsers and devices**.
- Consider future **extensibility**, avoiding tight coupling.
- Use **Shopify CLI** for local development and deployment.

## Quality and Testing
- Use **Shopify Theme Check** for static code analysis.
- Write **unit tests** (where applicable).
- Conduct thorough **end-to-end testing**.
- Test in various environments (local, development store, production store).
- Focus on **compatibility testing** (browsers, devices, Shopify versions).
- Test **error handling** and edge cases.