@americanexpress/one-app-bundler
v7.0.3
Published
A command line interface(CLI) tool for bundling One App and its modules.
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@americanexpress/one-app-bundler
A command line interface(CLI) tool for bundling One App and One App modules.
🤹 Usage
To bundle a One App module
To build a React component for usage as a One App module:
Install:
npm i -D @americanexpress/one-app-bundler
Run the bundle-module
script as part of your build. This script is provided by one-app-bundler
:
{
"scripts": {
"build": "bundle-module",
"prepare": "npm run build"
}
}
When bundling a One App module, some options can be applied by adding a bundler
config object to a one-amex
section
within package.json
:
{
"one-amex": {
"bundler": {
}
}
}
Watch Mode
The bundler supports automatically re-building on file changes via the --watch
flag. You can include an addition script for this:
{
"scripts": {
"watch:build": "bundle-module --watch"
}
}
Or pass the flag when running the build script:
npm run build -- --watch
Development Bundler
When working on One App modules locally, you can use the Development Bundler.
This bundler aims to provide <500ms build times, and Live Holocron Module Reload.
To enable the development bundler, pass the --dev
flag, either in your scripts:
{
"scripts": {
"build": "bundle-module --dev",
"prepare": "npm run build",
"watch:build": "bundle-module --watch --dev"
}
}
or on the command line:
npm run build -- --dev
The development bundler will only run if NODE_ENV !== 'production'
. This means you can include the flag for all builds, and for production
builds the Webpack bundler will be used.
Live Holocron Module Reload
When in watch mode, the Development Bundler can automatically re-load changed modules in your browser.
This allows you to see changes made to modules near instantly, with no full page re-load required.
This can be enabled with the --live
flag. The --live
flag also implies the --watch
flag so there is no need to pass both:
{
"scripts": {
"build": "bundle-module --dev",
"prepare": "npm run build",
"watch:build": "bundle-module --watch --dev",
"live:build": "bundle-module --live --dev"
}
}
npm run build -- --dev --live
providedExternals
& requiredExternals
In order to avoid duplicate code in your One App instance, you may want to
share a dependency across all your modules that is not already provided by One
App. These dependencies can be provided to your modules by your root
module. The root module should include in its configuration
providedExternals
. This will include and make the listed dependencies
available to be consumed by child modules. Child modules will use requiredExternals
to consume dependencies provided by the root modules providedExternals
, this will also remove
the dependency from the child modules bundle.
Modules shouldn't configure both providedExternals
and requiredExternals
.
Remember providedExternals
are dependencies which your root module will make available to child modules.
requiredExternals
are a list of dependencies the child module will need to be made available by the root module.
All modules requiredExternals
are validated at runtime against the root modules list of providedExternals
.
By default if the external dependency is not provided One App will throw an error. This will either result in the
One App server not starting or, if it is already running, One App will not load that module. For example, if your
child module requires ^2.1.0
of a dependency but your root module provides 2.0.0
, this will result in One App
not loading that child module as the provided dependencies version does not satisfy the required semantic range.
This ensures that all of the listed dependencies features, potentially required by the child module to work, will be provided which could result in hard to debug bugs.
If you attempt to include one of the dependencies provided by One App in your providedExternals
or requiredExternals
, your build will fail.
Externals Fallbacks
External fallbacks were added to help reduce the impact of some of the cons listed below.
For each dependency listed in requiredExternals
fallback bundles(browser and server) will
be created. If the root module permits these fallbacks will be used to enable that child
module to load when there is no valid provided external dependency. This can be helpful when
transitioning between major versions of a externals dependency.
To enable fallbacks the root module will need to set the fallbackEnabled
option to true
for each
provided external and the enableUnlistedExternalFallbacks
to allow fallbacks for unlisted
dependencies.
Usage
First make sure to add your dependency to your module's package.json
:
npm install some-dependency
Then configure one-app-bundler
to provide that dependency (and any others) as an external to your other modules:
{
"one-amex": {
"bundler": {
"providedExternals": {
"some-dependency": {
"fallbackEnabled": true
},
"another-dependency": {
"fallbackEnabled": false
}
}
}
}
}
Modules consuming these external dependencies must declare what they expect the
root module to provide by setting the requiredExternals
option. Any dependency
listed there will not be bundled with the module, but will be replaced with a
reference to the external dependency as provided by the root module.
Before doing so make sure to add said dependency to your package.json
:
npm install some-dependency
{
"one-amex": {
"bundler": {
"requiredExternals": ["some-dependency"]
}
}
}
Pros and Cons of Externals
Pros:
- Smaller module bundle size
- Can allow for centralized updates
- Easy security patches providing child module sem ver range permits
Cons:
- Lose treeshaking potentially causing larger bundle sizes
- For example, adding something like lodash as an external when only a small part of the library is used could result in the client having to download more than if the tree shaken versions were bundled with the module.
- Couples your child and root module together
- Increases complexity when managing updates to the provided and required dependency
enableUnlistedExternalFallbacks
To allow child modules to load when a requiredExternal
is not listed as a providedExternal
use the enableUnlistedExternalFallbacks
option.
The child module must provide a fallback bundle for the missing required external to load when this option is set.
enableUnlistedExternalFallbacks
defaults to false if unset.
{
"one-amex": {
"bundler": {
"enableUnlistedExternalFallbacks": true
}
}
}
performanceBudget
Set a custom performance budget
for your client module build. The default value is 250e3
(244kB).
{
"one-amex": {
"bundler": {
"performanceBudget": 500e3
}
}
}
webpackConfigPath, webpackClientConfigPath, & webpackServerConfigPath
You may extend the webpack configuration by providing paths to custom webpack config files in this option. Use of this option is at your own risk.
There are two options when customizing your webpack build.
- Add
webpackConfigPath
to apply a custom config to both your client and server builds.
{
"one-amex": {
"bundler": {
"webpackConfigPath": "webpack.config.js"
}
}
}
- Add
webpackClientConfigPath
and/orwebpackServerConfigPath
to apply different configs to your client and server builds. You don't need to add both of these options. You can pass only one if you wish to customize a single build target.
{
"one-amex": {
"bundler": {
"webpackClientConfigPath": "webpack.client.config.js",
"webpackServerConfigPath": "webpack.server.config.js"
}
}
}
purgecss
Options
purgecss
is an opt-in optimization that can reduce the overall bundle size of your module by
eliminating unused css from your module's bundle. You can enable purgecss
by setting
bundler.purgecss.enabled
to true
in the one-amex
key in your module's package.json
:
{
"one-amex": {
"bundler": {
"purgecss": {
"enabled": true
}
}
}
}
You may add additional paths for purgecss
to consider before stripping out
unused CSS by adding an array of glob patterns to bundler.purgecss.paths
under bundler.purgecss.paths
. The example below illustrates how we would add
some-lib
if we were applying custom styles to it in our module.
{
"one-amex": {
"bundler": {
"purgecss": {
"enabled": true,
"paths": ["node_modules/some-lib/src/**/*.{js,jsx}"]
}
}
}
}
Additional purgecss
options. Please refer to the purgecss Options Documentation
before enabling any of the following:
Simple usage of safelist
{
"one-amex": {
"bundler": {
"purgecss": {
"enabled": true,
"paths": ["node_modules/some-lib/src/**/*.{js,jsx}"],
"extractors": [{
"extractor": "purgeJs",
"extensions": [
"js"
]
}],
"fontFace": false,
"keyframes": false,
"variables": false,
"safelist": [
"random",
"yep",
"button"
],
"blocklist":["random"]
}
}
}
}
Complex usage of safelist
{
"one-amex": {
"bundler": {
"purgecss": {
"enabled": true,
"paths": ["node_modules/some-lib/src/**/*.{js,jsx}"],
"extractors": [{
"extractor": "purgeJs",
"extensions": [
"js"
]
}],
"fontFace": false,
"keyframes": false,
"variables": false,
"safelist": {
"standard": ["random"],
"deep": ["randomdeep"],
"greedy": ["randomgreedy"],
"keyframes": true,
"variables": true,
},
"blocklist":["random"]
}
}
}
}
Legacy browser support
disableDevelopmentLegacyBundle
can be added to your bundler config and set to true to opt out of bundling the legacy
assets. This will reduce bundle size and build times. This is only configured to be removed when in development
. production
builds will not skip the legacy
build.
Caution as this will remove legacy browser support from your module.
{
"one-amex": {
"bundler": {
"disableDevelopmentLegacyBundle": true
}
}
}
TypeScript
TypeScript in One App modules needs no extra configuration within one-app-bundler
to work. one-app-bundler
is set up to ignore TypeScript
features leaving tsc
to focus on typechecking only.
Specify what version of One App your module is compatible with
You can specify which version of One App you module is compatible with by simply adding the below configuration to your package.json
.
{
"one-amex": {
"app": {
"compatibility": "^5.0.0"
},
}
}