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Merge branch '43720-update-fe-webpack-docs' into 'master'

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Resolve "Document webpack_bundle_tag replacement method"

Closes #43720 and #42704

See merge request gitlab-org/gitlab-ce!17706
This commit is contained in:
Jacob Schatz 2018-03-13 11:34:12 +00:00
commit 9a1af4a39c
7 changed files with 112 additions and 62 deletions
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5
app/helpers/javascript_helper.rb
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@ -2,9 +2,4 @@ module JavascriptHelper
def page_specific_javascript_tag(js)
javascript_include_tag asset_path(js)
end
# deprecated; use webpack_bundle_tag directly instead
def page_specific_javascript_bundle_tag(bundle)
webpack_bundle_tag(bundle)
end
end

6
changelogs/unreleased/43720-update-fe-webpack-docs.yml Normal file
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@ -0,0 +1,6 @@
---
title: Update documentation to reflect current minimum required versions of node and
yarn
merge_request: 17706
author:
type: other

18
doc/development/ee_features.md
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@ -360,27 +360,15 @@ Instead place EE specs in the `ee/spec` folder.
## JavaScript code in `assets/javascripts/`
To separate EE-specific JS-files we can also move the files into an `ee` folder.
To separate EE-specific JS-files we should also move the files into an `ee` folder.
For example there can be an
`app/assets/javascripts/protected_branches/protected_branches_bundle.js` and an
EE counterpart
`ee/app/assets/javascripts/protected_branches/protected_branches_bundle.js`.
That way we can create a separate webpack bundle in `webpack.config.js`:
```javascript
protected_branches: '~/protected_branches',
ee_protected_branches: 'ee/protected_branches/protected_branches_bundle.js',
```
With the separate bundle in place, we can decide which bundle to load inside the
view, using the `page_specific_javascript_bundle_tag` helper.
```haml
- content_for :page_specific_javascripts do
= page_specific_javascript_bundle_tag('protected_branches')
```
See the frontend guide [performance section](./fe_guide/performance.md) for
information on managing page-specific javascript within EE.
## SCSS code in `assets/stylesheets`

4
doc/development/fe_guide/index.md
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@ -14,8 +14,8 @@ support through [webpack][webpack].
We also utilize [webpack][webpack] to handle the bundling, minification, and
compression of our assets.
Working with our frontend assets requires Node (v4.3 or greater) and Yarn
(v0.17 or greater). You can find information on how to install these on our
Working with our frontend assets requires Node (v6.0 or greater) and Yarn
(v1.2 or greater). You can find information on how to install these on our
[installation guide][install].
[jQuery][jquery] is used throughout the application's JavaScript, with

120
doc/development/fe_guide/performance.md
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@ -23,7 +23,7 @@ controlled by the server.
1. The backend code will most likely be using etags. You do not and should not check for status
`304 Not Modified`. The browser will transform it for you.
### Lazy Loading
### Lazy Loading Images
To improve the time to first render we are using lazy loading for images. This works by setting
the actual image source on the `data-src` attribute. After the HTML is rendered and JavaScript is loaded,
@ -47,41 +47,103 @@ properties once, and handle the actual animation with transforms.
## Reducing Asset Footprint
### Universal code
Code that is contained within `main.js` and `commons/index.js` are loaded and
run on _all_ pages. **DO NOT ADD** anything to these files unless it is truly
needed _everywhere_. These bundles include ubiquitous libraries like `vue`,
`axios`, and `jQuery`, as well as code for the main navigation and sidebar.
Where possible we should aim to remove modules from these bundles to reduce our
code footprint.
### Page-specific JavaScript
Certain pages may require the use of a third party library, such as [d3][d3] for
the User Activity Calendar and [Chart.js][chartjs] for the Graphs pages. These
libraries increase the page size significantly, and impact load times due to
bandwidth bottlenecks and the browser needing to parse more JavaScript.
Webpack has been configured to automatically generate entry point bundles based
on the file structure within `app/assets/javascripts/pages/*`. The directories
within the `pages` directory correspond to Rails controllers and actions. These
auto-generated bundles will be automatically included on the corresponding
pages.
In cases where libraries are only used on a few specific pages, we use
"page-specific JavaScript" to prevent the main `main.js` file from
becoming unnecessarily large.
For example, if you were to visit [gitlab.com/gitlab-org/gitlab-ce/issues](https://gitlab.com/gitlab-org/gitlab-ce/issues),
you would be accessing the `app/controllers/projects/issues_controller.rb`
controller with the `index` action. If a corresponding file exists at
`pages/projects/issues/index/index.js`, it will be compiled into a webpack
bundle and included on the page.
Steps to split page-specific JavaScript from the main `main.js`:
> **Note:** Previously we had encouraged the use of
> `content_for :page_specific_javascripts` within haml files, along with
> manually generated webpack bundles. However under this new system you should
> not ever need to manually add an entry point to the `webpack.config.js` file.
1. Create a directory for the specific page(s), e.g. `graphs/`.
1. In that directory, create a `namespace_bundle.js` file, e.g. `graphs_bundle.js`.
1. Add the new "bundle" file to the list of entry files in `config/webpack.config.js`.
- For example: `graphs: './graphs/graphs_bundle.js',`.
1. Move code reliant on these libraries into the `graphs` directory.
1. In `graphs_bundle.js` add CommonJS `require('./path_to_some_component.js');` statements to load any other files in this directory. Make sure to use relative urls.
1. In the relevant views, add the scripts to the page with the following:
> **Tip:**
> If you are unsure what controller and action corresponds to a given page, you
> can find this out by inspecting `document.body.dataset.page` within your
> browser's developer console while on any page within gitlab.
```haml
- content_for :page_specific_javascripts do
= webpack_bundle_tag 'lib_chart'
= webpack_bundle_tag 'graphs'
```
#### Important Considerations:
The above loads `chart.js` and `graphs_bundle.js` for this page only. `chart.js`
is separated from the bundle file so it can be cached separately from the bundle
and reused for other pages that also rely on the library. For an example, see
[this Haml file][page-specific-js-example].
- **Keep Entry Points Lite:**
Page-specific javascript entry points should be as lite as possible. These
files are exempt from unit tests, and should be used primarily for
instantiation and dependency injection of classes and methods that live in
modules outside of the entry point script. Just import, read the DOM,
instantiate, and nothing else.
- **Entry Points May Be Asynchronous:**
_DO NOT ASSUME_ that the DOM has been fully loaded and available when an
entry point script is run. If you require that some code be run after the
DOM has loaded, you should attach an event handler to the `DOMContentLoaded`
event with:
```javascript
import initMyWidget from './my_widget';
document.addEventListener('DOMContentLoaded', () => {
initMyWidget();
});
```
- **Supporting Module Placement:**
- If a class or a module is _specific to a particular route_, try to locate
it close to the entry point it will be used. For instance, if
`my_widget.js` is only imported within `pages/widget/show/index.js`, you
should place the module at `pages/widget/show/my_widget.js` and import it
with a relative path (e.g. `import initMyWidget from './my_widget';`).
- If a class or module is _used by multiple routes_, place it within a
shared directory at the closest common parent directory for the entry
points that import it. For example, if `my_widget.js` is imported within
both `pages/widget/show/index.js` and `pages/widget/run/index.js`, then
place the module at `pages/widget/shared/my_widget.js` and import it with
a relative path if possible (e.g. `../shared/my_widget`).
- **Enterprise Edition Caveats:**
For GitLab Enterprise Edition, page-specific entry points will override their
Community Edition counterparts with the same name, so if
`ee/app/assets/javascripts/pages/foo/bar/index.js` exists, it will take
precedence over `app/assets/javascripts/pages/foo/bar/index.js`. If you want
to minimize duplicate code, you can import one entry point from the other.
This is not done automatically to allow for flexibility in overriding
functionality.
### Code Splitting
> *TODO* flesh out this section once webpack is ready for code-splitting
For any code that does not need to be run immediately upon page load, (e.g.
modals, dropdowns, and other behaviors that can be lazy-loaded), you can split
your module into asynchronous chunks with dynamic import statements. These
imports return a Promise which will be resolved once the script has loaded:
```javascript
import(/* webpackChunkName: 'emoji' */ '~/emoji')
.then(/* do something */)
.catch(/* report error */)
```
Please try to use `webpackChunkName` when generating these dynamic imports as
it will provide a deterministic filename for the chunk which can then be cached
the browser across GitLab versions.
More information is available in [webpack's code splitting documentation](https://webpack.js.org/guides/code-splitting/#dynamic-imports).
### Minimizing page size
@ -95,7 +157,8 @@ General tips:
- Prefer font formats with better compression, e.g. WOFF2 is better than WOFF, which is better than TTF.
- Compress and minify assets wherever possible (For CSS/JS, Sprockets and webpack do this for us).
- If some functionality can reasonably be achieved without adding extra libraries, avoid them.
- Use page-specific JavaScript as described above to dynamically load libraries that are only needed on certain pages.
- Use page-specific JavaScript as described above to load libraries that are only needed on certain pages.
- Use code-splitting dynamic imports wherever possible to lazy-load code that is not needed initially.
- [High Performance Animations][high-perf-animations]
-------
@ -112,8 +175,5 @@ General tips:
[pagespeed-insights]: https://developers.google.com/speed/pagespeed/insights/
[google-devtools-profiling]: https://developers.google.com/web/tools/chrome-devtools/profile/?hl=en
[browser-diet]: https://browserdiet.com/
[d3]: https://d3js.org/
[chartjs]: http://www.chartjs.org/
[page-specific-js-example]: https://gitlab.com/gitlab-org/gitlab-ce/blob/13bb9ed77f405c5f6ee4fdbc964ecf635c9a223f/app/views/projects/graphs/_head.html.haml#L6-8
[high-perf-animations]: https://www.html5rocks.com/en/tutorials/speed/high-performance-animations/
[flip]: https://aerotwist.com/blog/flip-your-animations/

13
doc/install/installation.md
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@ -162,13 +162,14 @@ page](https://golang.org/dl).
## 4. Node
Since GitLab 8.17, GitLab requires the use of node >= v4.3.0 to compile
javascript assets, and yarn >= v0.17.0 to manage javascript dependencies.
In many distros the versions provided by the official package repositories
are out of date, so we'll need to install through the following commands:
Since GitLab 8.17, GitLab requires the use of Node to compile javascript
assets, and Yarn to manage javascript dependencies. The current minimum
requirements for these are node >= v6.0.0 and yarn >= v1.2.0. In many distros
the versions provided by the official package repositories are out of date, so
we'll need to install through the following commands:
# install node v7.x
curl --location https://deb.nodesource.com/setup_7.x | sudo bash -
# install node v8.x
curl --location https://deb.nodesource.com/setup_8.x | sudo bash -
sudo apt-get install -y nodejs
curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -

8
doc/update/10.5-to-10.6.md
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@ -56,8 +56,8 @@ sudo gem install bundler --no-ri --no-rdoc
### 4. Update Node
GitLab now runs [webpack](http://webpack.js.org) to compile frontend assets.
We require a minimum version of node v6.0.0.
GitLab utilizes [webpack](http://webpack.js.org) to compile frontend assets.
This requires a minimum version of node v6.0.0.
You can check which version you are running with `node -v`. If you are running
a version older than `v6.0.0` you will need to update to a newer version. You
@ -66,8 +66,8 @@ from source at the nodejs.org website.
<https://nodejs.org/en/download/>
Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
JavaScript dependencies.
GitLab also requires the use of yarn `>= v1.2.0` to manage JavaScript
dependencies.
```bash
curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -