react-native-lazy-index
is a Hermes/RAM bundle friendly, bundle-time generated
index.js
. Improve your app startup time by only loading features you'll use on
demand.
For information on RAM bundles and inline requires, see React Native Performance.
If you use Haul, also take a look at their documentation.
npm install --save @rnx-kit/react-native-lazy-index
react-native-lazy-index
uses
babel-plugin-codegen
,
so you'll need to configure Babel to include it. The recommended way is to add
it to your .babelrc
:
{
"presets": ["module:metro-react-native-babel-preset"],
"plugins": [
+ "codegen"
]
}
In your index.js
, import @rnx-kit/react-native-lazy-index
and pass to it the
features that should be lazy loaded. In the example below, we register four
entry points:
// @codegen
module.exports = require("@rnx-kit/react-native-lazy-index")({
SomeFeature: "@awesome-app/some-feature",
"callable:AnotherFeature": "@awesome-app/another-feature",
YetAnotherFeature: "@awesome-app/yet-another-feature",
FinalFeature: "@awesome-app/final-feature",
});
By default, a call to AppRegistry
is generated using the key as the app key,
and the value is the name of the module containing the app. If the key is
prefixed with callable:
, a call to BatchedBridge
will be generated.
That's it!
With a naive index.js
, all features will be loaded when your app starts and
React Native is initialized for the first time.
import "@awesome-app/some-feature";
import "@awesome-app/another-feature";
import "@awesome-app/yet-another-feature";
import "@awesome-app/final-feature";
By loading features on demand, we can improve app startup time.
With react-native-lazy-index
, we no longer load all features up front.
Instead, index.js
wraps calls to AppRegistry.registerComponent
and
BatchedBridge.registerCallableModule
, deferring the import of a feature until
it is used. Features that are never used, are never loaded.
When you import react-native-lazy-index
, something similar to below is
generated:
const { AppRegistry } = require("react-native");
const BatchedBridge = require("react-native/Libraries/BatchedBridge/BatchedBridge");
AppRegistry.registerComponent("SomeFeature", () => {
// We'll import the module the first time "SomeFeature" is accessed.
require("@awesome-app/some-feature");
// "SomeFeature" is now overwritten and we can return the real component.
// Subsequent calls to "SomeFeature" will no longer go through this wrapper.
return AppRegistry.getRunnable("SomeFeature").componentProvider();
});
BatchedBridge.registerLazyCallableModule("AnotherFeature", () => {
// We'll import the module the first time "AnotherFeature" is accessed.
require("@awesome-app/another-feature");
// "AnotherFeature" is now overwritten and we can return the real component.
// Subsequent calls to "AnotherFeature" will no longer go through this
// wrapper.
return BatchedBridge.getCallableModule("AnotherFeature");
});
AppRegistry.registerComponent("YetAnotherFeature", () => {
// We'll import the module the first time "YetAnotherFeature" is accessed.
require("@awesome-app/yet-another-feature");
// "YetAnotherFeature" is now overwritten and we can return the real
// component. Subsequent calls to "YetAnotherFeature" will no longer go
// through this wrapper.
return AppRegistry.getRunnable("YetAnotherFeature").componentProvider();
});
AppRegistry.registerComponent("FinalFeature", () => {
// We'll import the module the first time "FinalFeature" is accessed.
require("@awesome-app/final-feature");
// "FinalFeature" is now overwritten and we can return the real component.
// Subsequent calls to "FinalFeature" will no longer go through this wrapper.
return AppRegistry.getRunnable("FinalFeature").componentProvider();
});
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This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.