angular-ssr-element-preserver
v1.0.0
Published
This is a proof of concept, do not use in production!
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What this Does
This is a proof of concept, do not use in production!
This module is designed to protect a subset of elements in a pre-rendered Angular app, to reference and re-insert the elements after Angular has bootstrapped in the browser instead of destroying and recreating them.
There are limitations to this approach:
- If there are iframes inside the protected element (such as ads), the iframes will reload once re-inserted into the DOM after bootstrapped in the browser.
- Angular Bindings inside the protected element won't work after bootstrap in the browser, but the element will have the values that were bound when the page was pre-rendered (Angular Elements are an exception)
How to Use
Step 1: Install
npm install angular-ssr-element-preserverStep 2: Update app.module.ts:
import { ElementPreserverModule } from 'angular-ssr-element-preserver';
@NgModule({
...
imports: [
ElementPreserverModule.forBrowser(),
BrowserModule.withServerTransition({ appId: 'serverApp' }),
],
...
})
export class AppModule {}Step 4: Update app.server.module.ts:
import { ElementPreserverModule } from 'angular-ssr-element-preserver';
@NgModule({
imports: [AppModule, ServerModule, ElementPreserverModule.forServer()],
...
})
export class AppServerModule {}Step 4: Add this script before the closing in src/index.html
It's important that this script ends up inserted after all the pre-rendered elements, but before the Angular script tags that the Angular builder inserts.
<body>
<myapp-root></myapp-root>
<script type="text/javascript">
if (!window.__preservedElementsMap__) {
window.__preservedElementsMap__ = Array.prototype.reduce.call(
document.querySelectorAll('preserve-elements'),
(prev, curr, i) => {
let key = curr.getAttribute('__elPreserveKey');
return {
...prev,
[key]: curr,
};
},
{}
);
}
</script>
</body>Step 5: Add the PreserveElementsComponent around Components to Preserve and Reinsert
You must provide a unique key to the component, which will be used to track the element internally.
<preserve-elements [key]="'top-sidebar-recommendations'"> </preserve-elements>