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# Frontend Development Guidelines

This document describes various guidelines to ensure consistency and quality
across the GitLab frontend team.

## Overview

GitLab is built on top of [Ruby on Rails](https://rubyonrails.org). It uses [Haml](https://haml.info/) and a JavaScript-based frontend with [Vue.js](https://vuejs.org). If you are not sure when to use Vue on top of Haml-page, please read  [this explanation](vue.md#when-to-add-vue-application).

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Be wary of [the limitations that come with using Hamlit](https://github.com/k0kubun/hamlit/blob/master/REFERENCE.md#limitations).

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We also use [SCSS](https://sass-lang.com) and plain JavaScript with
modern ECMAScript standards supported through [Babel](https://babeljs.io/) and ES module support through [webpack](https://webpack.js.org/).

Working with our frontend assets requires Node (v12.22.1 or greater) and Yarn
(v1.10.0 or greater). You can find information on how to install these on our
[installation guide](../../install/installation.md#4-node).

### Browser Support

For supported browsers, see our [requirements](../../install/requirements.md#supported-web-browsers).

Use [BrowserStack](https://www.browserstack.com/) to test with our supported browsers.
Sign in to BrowserStack with the credentials saved in the **Engineering** vault of the GitLab
[shared 1Password account](https://about.gitlab.com/handbook/security/#1password-guide).

## Initiatives

You can find current frontend initiatives with a cross-functional impact on epics
with the label [frontend-initiative](https://gitlab.com/groups/gitlab-org/-/epics?state=opened&page=1&sort=UPDATED_AT_DESC&label_name[]=frontend-initiative).

## Principles

[High-level guidelines](principles.md) for contributing to GitLab.

## Development Process

How we [plan and execute](development_process.md) the work on the frontend.

## Architecture

How we go about [making fundamental design decisions](architecture.md) in the GitLab frontend team
or make changes to our frontend development guidelines.

## Testing

How we write [frontend tests](../testing_guide/frontend_testing.md), run the GitLab test suite, and debug test related
issues.

## Pajamas Design System

Reusable components with technical and usage guidelines can be found in our
[Pajamas Design System](https://design.gitlab.com/).

## Design Patterns

JavaScript [design patterns](design_patterns.md) in the GitLab codebase.

## Design Anti-patterns

JavaScript [design anti-patterns](design_anti_patterns.md) we try to avoid.

## Vue.js Best Practices

Vue specific [design patterns and practices](vue.md).

## Vuex

[Vuex](vuex.md) specific design patterns and practices.

## Axios

[Axios](axios.md) specific practices and gotchas.

## GraphQL

How to use [GraphQL](graphql.md).

## HAML

How to use [HAML](haml.md).

## ViewComponent

How we use [ViewComponent](view_component.md).

## Icons and Illustrations

How we use SVG for our [Icons and Illustrations](icons.md).

## Dependencies

General information about frontend [dependencies](dependencies.md) and how we manage them.

## Keyboard Shortcuts

How we implement [keyboard shortcuts](keyboard_shortcuts.md) that can be customized and disabled.

## Editors

GitLab text editing experiences are provided by the [Source Editor](source_editor.md) and
the [Content Editor](content_editor.md).

## Frontend FAQ

Read the [frontend's FAQ](frontend_faq.md) for common small pieces of helpful information.

## Style Guides

See the relevant style guides for our guidelines and for information on linting:

- [JavaScript](style/javascript.md). Our guide is based on
the excellent [Airbnb](https://github.com/airbnb/javascript) style guide with a few small
changes.
- [SCSS](style/scss.md): [our SCSS conventions](https://gitlab.com/gitlab-org/frontend/gitlab-stylelint-config) which are enforced through [`stylelint`](https://stylelint.io).
- [HTML](style/html.md). Guidelines for writing HTML code consistent with the rest of the codebase.
- [Vue](style/vue.md). Guidelines and conventions for Vue code may be found here.

## [Tooling](tooling.md)

Our code is automatically formatted with [Prettier](https://prettier.io) to follow our guidelines. Read our [Tooling guide](tooling.md) for more detail.

## [Performance](performance.md)

Best practices for monitoring and maximizing frontend performance.

## [Security](security.md)

Frontend security practices.

## Accessibility

Our [accessibility standards and resources](accessibility.md).

## Logging

Best practices for [client-side logging](logging.md) for GitLab frontend development.

## [Internationalization (i18n) and Translations](../i18n/externalization.md)

Frontend internationalization support is described in [this document](../i18n/index.md).
The [externalization part of the guide](../i18n/externalization.md) explains the helpers/methods available.

## [Troubleshooting](troubleshooting.md)

Running into a Frontend development problem? Check out [this guide](troubleshooting.md) to help resolve your issue.