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Merge branch '31552-documentation-dos-and-donts' into 'master' 

Resolve "Documentation: Frontend list of do's and don'ts"

Closes #31552

See merge request !11091
parents 709d70a7 6f040230
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doc/development/fe_guide/style_guide_js.md
View file @ 8d059643
......@@ -11,207 +11,205 @@ See [our current .eslintrc][eslintrc] for specific rules and patterns.
#### ESlint
- **Never** disable eslint rules unless you have a good reason. You may see a lot of legacy files with `/* eslint-disable some-rule, some-other-rule */` at the top, but legacy files are a special case. Any time you develop a new feature or refactor an existing one, you should abide by the eslint rules.
- **Never Ever EVER** disable eslint globally for a file
1. **Never** disable eslint rules unless you have a good reason.
You may see a lot of legacy files with `/* eslint-disable some-rule, some-other-rule */`
at the top, but legacy files are a special case. Any time you develop a new feature or
refactor an existing one, you should abide by the eslint rules.
1. **Never Ever EVER** disable eslint globally for a file
```javascript
// bad
/* eslint-disable */
// bad
/* eslint-disable */
// better
/* eslint-disable some-rule, some-other-rule */
// better
/* eslint-disable some-rule, some-other-rule */
// best
// nothing :)
// best
// nothing :)
```
- If you do need to disable a rule for a single violation, try to do it as locally as possible
1. If you do need to disable a rule for a single violation, try to do it as locally as possible
```javascript
// bad
/* eslint-disable no-new */
// bad
/* eslint-disable no-new */
import Foo from 'foo';
import Foo from 'foo';
new Foo();
new Foo();
// better
import Foo from 'foo';
// better
import Foo from 'foo';
// eslint-disable-next-line no-new
new Foo();
// eslint-disable-next-line no-new
new Foo();
```
1. There are few rules that we need to disable due to technical debt. Which are:
1. [no-new][eslint-new]
1. [class-methods-use-this][eslint-this]
- When they are needed _always_ place ESlint directive comment blocks on the first line of a script, followed by any global declarations, then a blank newline prior to any imports or code.
1. When they are needed _always_ place ESlint directive comment blocks on the first line of a script,
followed by any global declarations, then a blank newline prior to any imports or code.
```javascript
// bad
/* global Foo */
/* eslint-disable no-new */
import Bar from './bar';
// bad
/* global Foo */
/* eslint-disable no-new */
import Bar from './bar';
// good
/* eslint-disable no-new */
/* global Foo */
// good
/* eslint-disable no-new */
/* global Foo */
import Bar from './bar';
import Bar from './bar';
```
- **Never** disable the `no-undef` rule. Declare globals with `/* global Foo */` instead.
- When declaring multiple globals, always use one `/* global [name] */` line per variable.
1. **Never** disable the `no-undef` rule. Declare globals with `/* global Foo */` instead.
1. When declaring multiple globals, always use one `/* global [name] */` line per variable.
```javascript
// bad
/* globals Flash, Cookies, jQuery */
// bad
/* globals Flash, Cookies, jQuery */
// good
/* global Flash */
/* global Cookies */
/* global jQuery */
// good
/* global Flash */
/* global Cookies */
/* global jQuery */
```
- Use up to 3 parameters for a function or class. If you need more accept an Object instead.
1. Use up to 3 parameters for a function or class. If you need more accept an Object instead.
```javascript
// bad
fn(p1, p2, p3, p4) {}
// bad
fn(p1, p2, p3, p4) {}
// good
fn(options) {}
// good
fn(options) {}
```
#### Modules, Imports, and Exports
- Use ES module syntax to import modules
1. Use ES module syntax to import modules
```javascript
// bad
require('foo');
// bad
require('foo');
// good
import Foo from 'foo';
// good
import Foo from 'foo';
// bad
module.exports = Foo;
// bad
module.exports = Foo;
// good
export default Foo;
// good
export default Foo;
```
- Relative paths
Unless you are writing a test, always reference other scripts using relative paths instead of `~`
1. Relative paths: Unless you are writing a test, always reference other scripts using
relative paths instead of `~`
* In **app/assets/javascripts**:
In **app/assets/javascripts**:
```javascript
// bad
import Foo from '~/foo'
// good
import Foo from '../foo';
```
```javascript
// bad
import Foo from '~/foo'
In **spec/javascripts**:
```javascript
// bad
import Foo from '../../app/assets/javascripts/foo'
// good
import Foo from '../foo';
```
* In **spec/javascripts**:
// good
import Foo from '~/foo';
```
```javascript
// bad
import Foo from '../../app/assets/javascripts/foo'
- Avoid using IIFE. Although we have a lot of examples of files which wrap their contents in IIFEs (immediately-invoked function expressions), this is no longer necessary after the transition from Sprockets to webpack. Do not use them anymore and feel free to remove them when refactoring legacy code.
// good
import Foo from '~/foo';
```
- Avoid adding to the global namespace.
1. Avoid using IIFE. Although we have a lot of examples of files which wrap their
contents in IIFEs (immediately-invoked function expressions),
this is no longer necessary after the transition from Sprockets to webpack.
Do not use them anymore and feel free to remove them when refactoring legacy code.
1. Avoid adding to the global namespace.
```javascript
// bad
window.MyClass = class { /* ... */ };
// bad
window.MyClass = class { /* ... */ };
// good
export default class MyClass { /* ... */ }
// good
export default class MyClass { /* ... */ }
```
- Side effects are forbidden in any script which contains exports
1. Side effects are forbidden in any script which contains exports
```javascript
// bad
export default class MyClass { /* ... */ }
// bad
export default class MyClass { /* ... */ }
document.addEventListener("DOMContentLoaded", function(event) {
new MyClass();
}
document.addEventListener("DOMContentLoaded", function(event) {
new MyClass();
}
```
#### Data Mutation and Pure functions
- Strive to write many small pure functions, and minimize where mutations occur.
1. Strive to write many small pure functions, and minimize where mutations occur.
```javascript
// bad
const values = {foo: 1};
// bad
const values = {foo: 1};
function impureFunction(items) {
const bar = 1;
function impureFunction(items) {
const bar = 1;
items.foo = items.a * bar + 2;
items.foo = items.a * bar + 2;
return items.a;
}
return items.a;
}
const c = impureFunction(values);
const c = impureFunction(values);
// good
var values = {foo: 1};
// good
var values = {foo: 1};
function pureFunction (foo) {
var bar = 1;
function pureFunction (foo) {
var bar = 1;
foo = foo * bar + 2;
foo = foo * bar + 2;
return foo;
}
return foo;
}
var c = pureFunction(values.foo);
var c = pureFunction(values.foo);
```
- Avoid constructors with side-effects
1. Avoid constructors with side-effects
- Prefer `.map`, `.reduce` or `.filter` over `.forEach`
1. Prefer `.map`, `.reduce` or `.filter` over `.forEach`
A forEach will cause side effects, it will be mutating the array being iterated. Prefer using `.map`,
`.reduce` or `.filter`
```javascript
const users = [ { name: 'Foo' }, { name: 'Bar' } ];
const users = [ { name: 'Foo' }, { name: 'Bar' } ];
// bad
users.forEach((user, index) => {
user.id = index;
});
// bad
users.forEach((user, index) => {
user.id = index;
});
// good
const usersWithId = users.map((user, index) => {
return Object.assign({}, user, { id: index });
});
// good
const usersWithId = users.map((user, index) => {
return Object.assign({}, user, { id: index });
});
```
#### Parse Strings into Numbers
- `parseInt()` is preferable over `Number()` or `+`
1. `parseInt()` is preferable over `Number()` or `+`
```javascript
// bad
+'10' // 10
// bad
+'10' // 10
// good
Number('10') // 10
// good
Number('10') // 10
// better
parseInt('10', 10);
// better
parseInt('10', 10);
```
#### CSS classes used for JavaScript
- If the class is being used in Javascript it needs to be prepend with `js-`
1. If the class is being used in Javascript it needs to be prepend with `js-`
```html
// bad
<button class="add-user">
......@@ -226,234 +224,270 @@ A forEach will cause side effects, it will be mutating the array being iterated.
### Vue.js
#### Basic Rules
- Only include one Vue.js component per file.
- Export components as plain objects:
1. The service has it's own file
1. The store has it's own file
1. Use a function in the bundle file to instantiate the Vue component:
```javascript
export default {
template: `<h1>I'm a component</h1>
}
```
// bad
class {
init() {
new Component({})
}
}
#### Naming
- **Extensions**: Use `.vue` extension for Vue components.
- **Reference Naming**: Use PascalCase for Vue components and camelCase for their instances:
// good
document.addEventListener('DOMContentLoaded', () => new Vue({
el: '#element',
components: {
componentName
},
render: createElement => createElement('component-name'),
}));
```
1. Don not use a singleton for the service or the store
```javascript
// bad
import cardBoard from 'cardBoard';
// bad
class Store {
constructor() {
if (!this.prototype.singleton) {
// do something
}
}
}
// good
import CardBoard from 'cardBoard'
// good
class Store {
constructor() {
// do something
}
}
```
// bad
components: {
CardBoard: CardBoard
};
#### Naming
1. **Extensions**: Use `.vue` extension for Vue components.
1. **Reference Naming**: Use camelCase for their instances:
```javascript
// good
import cardBoard from 'cardBoard'
// good
components: {
cardBoard: CardBoard
};
components: {
cardBoard:
};
```
- **Props Naming:**
- Avoid using DOM component prop names.
- Use kebab-case instead of camelCase to provide props in templates.
1. **Props Naming:** Avoid using DOM component prop names.
1. **Props Naming:** Use kebab-case instead of camelCase to provide props in templates.
```javascript
// bad
<component class="btn">
// bad
<component class="btn">
// good
<component css-class="btn">
// good
<component css-class="btn">
// bad
<component myProp="prop" />
// bad
<component myProp="prop" />
// good
<component my-prop="prop" />
```
// good
<component my-prop="prop" />
```
#### Alignment
- Follow these alignment styles for the template method:
1. Follow these alignment styles for the template method:
```javascript
// bad
<component v-if="bar"
param="baz" />
// bad
<component v-if="bar"
param="baz" />
<button class="btn">Click me</button>
<button class="btn">Click me</button>
// good
<component
v-if="bar"
param="baz"
/>
// good
<component
v-if="bar"
param="baz"
/>
<button class="btn">
Click me
</button>
<button class="btn">
Click me
</button>
// if props fit in one line then keep it on the same line
<component bar="bar" />
// if props fit in one line then keep it on the same line
<component bar="bar" />
```
#### Quotes
- Always use double quotes `"` inside templates and single quotes `'` for all other JS.
1. Always use double quotes `"` inside templates and single quotes `'` for all other JS.
```javascript
// bad
template: `
<button :class='style'>Button</button>
`
// good
template: `
<button :class="style">Button</button>
`
// bad
template: `
<button :class='style'>Button</button>
`
// good
template: `
<button :class="style">Button</button>
`
```
#### Props
- Props should be declared as an object
1. Props should be declared as an object
```javascript
// bad
props: ['foo']
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
// bad
props: ['foo']
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
}
}
}
```
- Required key should always be provided when declaring a prop
1. Required key should always be provided when declaring a prop
```javascript
// bad
props: {
foo: {
type: String,
// bad
props: {
foo: {
type: String,
}
}
}
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
}
}
}
```
- Default key should always be provided if the prop is not required:
1. Default key should always be provided if the prop is not required:
```javascript
// bad
props: {
foo: {
type: String,
required: false,
// bad
props: {
foo: {
type: String,
required: false,
}
}
}
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
// good
props: {
foo: {
type: String,
required: false,
default: 'bar'
}
}
}
// good
props: {
foo: {
type: String,
required: true
// good
props: {
foo: {
type: String,
required: true
}
}
}
```
#### Data
- `data` method should always be a function
1. `data` method should always be a function
```javascript
// bad
data: {
foo: 'foo'
}
// good
data() {
return {
// bad
data: {
foo: 'foo'
};
}
}
// good
data() {
return {
foo: 'foo'
};
}
```
#### Directives
- Shorthand `@` is preferable over `v-on`
1. Shorthand `@` is preferable over `v-on`
```javascript
// bad
<component v-on:click="eventHandler"/>
// bad
<component v-on:click="eventHandler"/>
// good
<component @click="eventHandler"/>
// good
<component @click="eventHandler"/>
```
- Shorthand `:` is preferable over `v-bind`
1. Shorthand `:` is preferable over `v-bind`
```javascript
// bad
<component v-bind:class="btn"/>
// bad
<component v-bind:class="btn"/>
// good
<component :class="btn"/>
// good
<component :class="btn"/>
```
#### Closing tags
- Prefer self closing component tags
1. Prefer self closing component tags
```javascript
// bad
<component></component>
// bad
<component></component>
// good
<component />
// good
<component />
```
#### Ordering
- Order for a Vue Component:
1. Order for a Vue Component:
1. `name`
2. `props`
3. `data`
4. `components`
5. `computedProps`
6. `methods`
7. lifecycle methods
1. `beforeCreate`
2. `created`
3. `beforeMount`
4. `mounted`
5. `beforeUpdate`
6. `updated`
7. `activated`
8. `deactivated`
9. `beforeDestroy`
10. `destroyed`
8. `template`
1. `props`
1. `mixins`
1. `data`
1. `components`
1. `computedProps`
1. `methods`
1. `beforeCreate`
1. `created`
1. `beforeMount`
1. `mounted`
1. `beforeUpdate`
1. `updated`
1. `activated`
1. `deactivated`
1. `beforeDestroy`
1. `destroyed`
#### Vue and Boostrap
1. Tooltips: Do not rely on `has-tooltip` class name for vue components
```javascript
// bad
<span class="has-tooltip">
Text
</span>
// good
<span data-toggle="tooltip">
Text
</span>
```
1. Tooltips: When using a tooltip, include the tooltip mixin
1. Don't change `data-original-title`.
```javascript
// bad
<span data-original-title="tooltip text">Foo</span>
// good
<span title="tooltip text">Foo</span>
$('span').tooltip('fixTitle');
```
## SCSS
......@@ -461,3 +495,5 @@ A forEach will cause side effects, it will be mutating the array being iterated.
[airbnb-js-style-guide]: https://github.com/airbnb/javascript
[eslintrc]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/.eslintrc
[eslint-this]: http://eslint.org/docs/rules/class-methods-use-this
[eslint-new]: http://eslint.org/docs/rules/no-new
doc/development/fe_guide/vue.md
View file @ 8d059643
......@@ -387,6 +387,10 @@ describe('Todos App', () => {
});
});
```
#### Test the component's output
The main return value of a Vue component is the rendered output. In order to test the component we
need to test the rendered output. [Vue][vue-test] guide's to unit test show us exactly that:
### Stubbing API responses
[Vue Resource Interceptors][vue-resource-interceptor] allow us to add a interceptor with
......@@ -419,6 +423,16 @@ the response we need:
});
```
1. Use `$.mount()` to mount the component
```javascript
// bad
new Component({
el: document.createElement('div')
});
// good
new Component().$mount();
```
[vue-docs]: http://vuejs.org/guide/index.html
[issue-boards]: https://gitlab.com/gitlab-org/gitlab-ce/tree/master/app/assets/javascripts/boards
......@@ -429,5 +443,6 @@ the response we need:
[one-way-data-flow]: https://vuejs.org/v2/guide/components.html#One-Way-Data-Flow
[vue-resource-repo]: https://github.com/pagekit/vue-resource
[vue-resource-interceptor]: https://github.com/pagekit/vue-resource/blob/develop/docs/http.md#interceptors
[vue-test]: https://vuejs.org/v2/guide/unit-testing.html
[issue-boards-service]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/boards/services/board_service.js.es6
[flux]: https://facebook.github.io/flux
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