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	1. Add some general guidelines how to write our typescript code 2. Add `@typescript-eslint/eslint-plugin`, general typescript rules 3. Add `eslint-plugin-deprecation` to detect deprecated code 4. Fix all new lint issues that came up
		
			
				
	
	
		
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			Markdown
		
	
	
	
	
	
			
		
		
	
	
			166 lines
		
	
	
		
			8.0 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
| ---
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| date: "2021-10-13T16:00:00+02:00"
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| title: "Guidelines for Frontend Development"
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| slug: "guidelines-frontend"
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| sidebar_position: 30
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| toc: false
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| draft: false
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| aliases:
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|   - /en-us/guidelines-frontend
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| menu:
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|   sidebar:
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|     parent: "contributing"
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|     name: "Guidelines for Frontend"
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|     sidebar_position: 30
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|     identifier: "guidelines-frontend"
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| ---
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| 
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| # Guidelines for Frontend Development
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| 
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| ## Background
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| 
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| Gitea uses [Fomantic-UI](https://fomantic-ui.com/introduction/getting-started.html) (based on [jQuery](https://api.jquery.com)) and [Vue3](https://vuejs.org/) for its frontend.
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| 
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| The HTML pages are rendered by [Go HTML Template](https://pkg.go.dev/html/template).
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| 
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| The source files can be found in the following directories:
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| 
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| * **CSS styles:** `web_src/css/`
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| * **JavaScript files:** `web_src/js/`
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| * **Vue components:** `web_src/js/components/`
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| * **Go HTML templates:** `templates/`
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| 
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| ## General Guidelines
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| 
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| We recommend [Google HTML/CSS Style Guide](https://google.github.io/styleguide/htmlcssguide.html) and [Google JavaScript Style Guide](https://google.github.io/styleguide/jsguide.html)
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| 
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| ### Gitea specific guidelines
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| 
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| 1. Every feature (Fomantic-UI/jQuery module) should be put in separate files/directories.
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| 2. HTML ids and classes should use kebab-case, it's preferred to contain 2-3 feature related keywords.
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| 3. HTML ids and classes used in JavaScript should be unique for the whole project, and should contain 2-3 feature related keywords. We recommend to use the `js-` prefix for classes that are only used in JavaScript.
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| 4. CSS styling for classes provided by frameworks should not be overwritten. Always use new class names with 2-3 feature related keywords to overwrite framework styles. Gitea's helper CSS classes in `helpers.less` could be helpful.
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| 5. The backend can pass complex data to the frontend by using `ctx.PageData["myModuleData"] = map[]{}`, but do not expose whole models to the frontend to avoid leaking sensitive data.
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| 6. Simple pages and SEO-related pages use Go HTML Template render to generate static Fomantic-UI HTML output. Complex pages can use Vue3.
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| 7. Clarify variable types, prefer `elem.disabled = true` instead of `elem.setAttribute('disabled', 'anything')`, prefer `$el.prop('checked', var === 'yes')` instead of `$el.prop('checked', var)`.
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| 8. Use semantic elements, prefer `<button class="ui button">` instead of `<div class="ui button">`.
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| 9. Avoid unnecessary `!important` in CSS, add comments to explain why it's necessary if it can't be avoided.
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| 10. Avoid mixing different events in one event listener, prefer to use individual event listeners for every event.
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| 11. Custom event names are recommended to use `ce-` prefix.
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| 12. Prefer using Tailwind CSS which is available via `tw-` prefix, e.g. `tw-relative`. Gitea's helper CSS classes use `gt-` prefix (`gt-ellipsis`), while Gitea's own private framework-level CSS classes use `g-` prefix (`g-modal-confirm`).
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| 13. Avoid inline scripts & styles as much as possible, it's recommended to put JS code into JS files and use CSS classes. If inline scripts & styles are unavoidable, explain the reason why it can't be avoided.
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| 
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| ### Accessibility / ARIA
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| 
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| In history, Gitea heavily uses Fomantic UI which is not an accessibility-friendly framework.
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| Gitea uses some patches to make Fomantic UI more accessible (see `aria.md` and related JS files),
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| but there are still many problems which need a lot of work and time to fix.
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| 
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| ### Framework Usage
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| 
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| Mixing different frameworks together is discouraged, it makes the code difficult to be maintained.
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| A JavaScript module should follow one major framework and follow the framework's best practice.
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| 
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| Recommended implementations:
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| 
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| * Vue + Vanilla JS
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| * Fomantic-UI (jQuery)
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| * htmx (partial page reloads for otherwise static components)
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| * Vanilla JS
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| 
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| Discouraged implementations:
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| 
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| * Vue + Fomantic-UI (jQuery)
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| * jQuery + Vanilla JS
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| * htmx + any other framework which requires heavy JS code, or unnecessary features like htmx scripting (`hx-on`)
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| 
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| To make UI consistent, Vue components can use Fomantic-UI CSS classes.
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| We use htmx for simple interactions. You can see an example for simple interactions where htmx should be used in this [PR](https://github.com/go-gitea/gitea/pull/28908). Do not use htmx if you require more advanced reactivity, use another framework (Vue/Vanilla JS).
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| Although mixing different frameworks is discouraged,
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| it should also work if the mixing is necessary and the code is well-designed and maintainable.
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| 
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| ### Typescript
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| 
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| Gitea is in the process of migrating to type-safe Typescript. Here are some specific guidelines regarding Typescript in the codebase:
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| 
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| #### Use type aliases instead of interfaces
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| 
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| Prefer to use type aliases because they can represent any type and are generally more flexible to use than interfaces.
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| 
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| #### Use separate type imports
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| 
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| We use `verbatimModuleSyntax` so type and non-type imports from the same file must be split into two `import type` statements. This enables the typescript compiler to completely eliminate the type import statements during compilation.
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| 
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| #### Use `@ts-expect-error` instead of `@ts-ignore`
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| 
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| Both annotations should be avoided, but if you have to use them, use `@ts-expect-error` because it will not leave ineffective statements after the issue is fixed.
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| 
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| ### `async` Functions
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| 
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| Only mark a function as `async` if and only if there are `await` calls
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| or `Promise` returns inside the function.
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| 
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| It's not recommended to use `async` event listeners, which may lead to problems.
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| The reason is that the code after await is executed outside the event dispatch.
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| Reference: https://github.com/github/eslint-plugin-github/blob/main/docs/rules/async-preventdefault.md
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| 
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| If an event listener must be `async`, the `e.preventDefault()` should be before any `await`,
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| it's recommended to put it at the beginning of the function.
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| 
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| If we want to call an `async` function in a non-async context,
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| it's recommended to use `const _promise = asyncFoo()` to tell readers
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| that this is done by purpose, we want to call the async function and ignore the Promise.
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| Some lint rules and IDEs also have warnings if the returned Promise is not handled.
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| 
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| ### Fetching data
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| 
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| To fetch data, use the wrapper functions `GET`, `POST` etc. from `modules/fetch.js`. They
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| accept a `data` option for the content, will automatically set CSRF token and return a
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| Promise for a [Response](https://developer.mozilla.org/en-US/docs/Web/API/Response).
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| 
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| ### HTML Attributes and `dataset`
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| 
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| The usage of `dataset` is forbidden, its camel-casing behaviour makes it hard to grep for attributes.
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| However, there are still some special cases, so the current guideline is:
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| 
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| * For legacy code:
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|   * `$.data()` should be refactored to `$.attr()`.
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|   * `$.data()` can be used to bind some non-string data to elements in rare cases, but it is highly discouraged.
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| 
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| * For new code:
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|   * `node.dataset` should not be used, use `node.getAttribute` instead.
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|   * never bind any user data to a DOM node, use a suitable design pattern to describe the relation between node and data.
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| 
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| ### Show/Hide Elements
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| 
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| * Vue components are recommended to use `v-if` and `v-show` to show/hide elements.
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| * Go template code should use `.tw-hidden` and `showElem()/hideElem()/toggleElem()`, see more details in `.tw-hidden`'s comment.
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| 
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| ### Styles and Attributes in Go HTML Template
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| 
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| It's recommended to use:
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| 
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| ```html
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| <div class="gt-name1 gt-name2 {{if .IsFoo}}gt-foo{{end}}" {{if .IsFoo}}data-foo{{end}}></div>
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| ```
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| 
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| instead of:
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| 
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| ```html
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| <div class="gt-name1 gt-name2{{if .IsFoo}} gt-foo{{end}}"{{if .IsFoo}} data-foo{{end}}></div>
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| ```
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| 
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| to make the code more readable.
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| 
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| ### Legacy Code
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| 
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| A lot of legacy code already existed before this document's written. It's recommended to refactor legacy code to follow the guidelines.
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| 
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| ### Vue3 and JSX
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| 
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| Gitea is using Vue3 now. We decided not to introduce JSX to keep the HTML and the JavaScript code separated.
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| 
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| ### UI Examples
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| 
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| Gitea uses some self-made UI elements and customizes others to integrate them better into the general UI approach. When running Gitea in development mode (`RUN_MODE=dev`), a page with some standardized UI examples is available under `http(s)://your-gitea-url:port/devtest`.
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