Are you looking for a lazyload component for your Angular application. If so, in this article I will share a simple Angular lazy loading plugin that supports dynamic lazy loading. You can dynamically fetch images and integrate this dynamic lazy loadable component.
Installation
Install via npm;
npm i ngx-loadable-component
* unfortunately, only an aot build angular setup will work correctly within the loadable component setup 🤷 ️ .. an example of how this is setup can be seen within the base directory of this repo(app demo)
Setup
Create a component you wish to dynamically load… e.g. loadable component
upside-down-face-emoji.component.ts
@Component({ selector: 'app-upside-down-face-emoji' ... }) export class UpsideDownFaceEmojiComponent { }
* its important that this component does not use OnPush
changeDetection as this will interfere with the loadable component setup
Then create a module for the loadable component:
upside-down-face-emoji.module.ts
import { LoadableComponentModule } from 'ngx-loadable-component'; import { UpsideDownFaceEmojiComponent } from './upside-down-face-emoji.component'; @NgModule({ imports: [ // register as loadable component LoadableComponentModule.forChild(UpsideDownFaceEmojiComponent) ], declarations: [UpsideDownFaceEmojiComponent] }) export class UpsideDownFaceEmojiComponentModule {}
Create a manifest file which lists all your loadable components:
app-loadable.manifests.ts
import { LoadableManifest } from 'ngx-loadable-component'; export enum LoadableComponentIds { UPSIDE_DOWN_FACE = 'UpsideDownFaceEmojiComponent' } export const appLoadableManifests: Array<LoadableManifest> = [ { // used to retrieve the loadable component later componentId: LoadableComponentIds.UPSIDE_DOWN_FACE, // must be a unique value within the app... // but apart from that only used by angular when loading component path: `loadable-${LoadableComponentIds.UPSIDE_DOWN_FACE}`, // relative path to component module loadChildren: './components/upside-down-face-emoji/upside-down-face-emoji.module#UpsideDownFaceEmojiComponentModule' } ];
Add the loadable component manifest & loadable component module to root app module:
app.module.ts
import { LoadableComponentModule } from 'ngx-loadable-component'; // loadable components manifest import { appLoadableManifests } from './app-loadable.manifests'; @NgModule({ declarations: [ ... ], imports: [ ... // components to load as seperate async LoadableComponentModule.forRoot(appLoadableManifests) ], providers: [], bootstrap: [AppComponent] }) export class AppModule { }
Be sure to import the loadable component module into any feature modules you use it in:
my-feature.module.ts
import { LoadableComponentModule } from 'ngx-loadable-component'; @NgModule({ declarations: [ ... ], imports: [ ... LoadableComponentModule.forFeature() ] }) export class MyFeatureModule { }
Usage (basic)
Add a loadable component where needed:
app.component.html
<div class="app--emojis"> <loadable-component [componentId]="UPSIDE_DOWN_FACE_COMPONENT_ID" [loadComponent]="loadUpsideDownFaceComponent"> <!-- any element in the loadable component content area will only be shown whilst loadComponent is false --> <app-placeholder-emoji></app-placeholder-emoji> </loadable-component> </div>
app.component.ts
import { LoadableComponentIds } from '../../app-loadable.manifests'; @Component({ ... }) export class AppComponent { // loadable component ids UPSIDE_DOWN_FACE_COMPONENT_ID: string = LoadableComponentIds.UPSIDE_DOWN_FACE; // flags to load components // setting this to 'true' will cause the loadable component // to load the specified component id loadUpsideDownFaceComponent: boolean = false; }
Usage (with Inputs/Outputs)
If our loadable component has inputs/outputs – like so:
upside-down-face-emoji.component.html
<a (click)="onClick()"> <div>🙃</div> <div>{{ text }}</div> </a>
upside-down-face-emoji.component.ts
export class UpsideDownFaceEmojiComponent { @Input() text: string = 'upside down'; @Output() clicked: EventEmitter<string> = new EventEmitter<string>(); constructor() {} onClick(): void { this.clicked.emit(this.text); } }
We then create a model representing the inputs/outputs (for some typing goodness 💯):
upside-down-face-emoji.inputs.model.ts
import { LoadableComponentInputs } from 'ngx-loadable-component'; export interface UpsideDownFaceEmojiComponentInputs extends LoadableComponentInputs { text: string; }
upside-down-face-emoji.outputs.model.ts
import { LoadableComponentOutputs } from 'ngx-loadable-component'; export interface UpsideDownFaceEmojiComponentOutputs extends LoadableComponentOutputs { clicked: Function; }
And add our inputs/outputs to the loadable component wherever its used:
app.component.html
<div class="app--emojis"> <loadable-component [componentId]="UPSIDE_DOWN_FACE_COMPONENT_ID" [loadComponent]="loadUpsideDownFaceComponent" [componentInputs]="upsideDownFaceInputs" [componentOutputs]="upsideDownFaceOutputs"> <!-- any element in the loadable component content area will only be shown whilst loadComponent is false --> <app-placeholder-emoji></app-placeholder-emoji> </loadable-component> </div>
app.component.ts
import { LoadableComponentIds } from '../../app-loadable.manifests'; import { UpsideDownFaceEmojiComponentInputs } from '../../components/upside-down-face-emoji/models/upside-down-face-emoji.inputs.model'; import { UpsideDownFaceEmojiComponentOutputs } from '../../components/upside-down-face-emoji/models/upside-down-face-emoji.outputs.model'; @Component({ ... }) export class AppComponent { // loadable component ids UPSIDE_DOWN_FACE_COMPONENT_ID: string = LoadableComponentIds.UPSIDE_DOWN_FACE; // flags to load components // setting this to 'true' will cause the loadable component // to load the specified component id loadUpsideDownFaceComponent: boolean = false; // inputs for loadable component get upsideDownFaceInputs(): UpsideDownFaceEmojiComponentInputs { return { text: 'not upside down' } } // outputs for loadable component get upsideDownFaceOutputs(): UpsideDownFaceEmojiComponentOutputs { return { clicked: (text: string) => this.onClickedUpsideDownFace(text) } } onClickedUpsideDownFace(text: string): void { console.log('🖱', text); } }
And voila! we now have input/output binding 👌. * note that the inputs in the parent component (of the loadable component – e.g. upsideDownFaceInputs()
) have to be within a getter or function for change detection to apply correctly
Usage (add custom css classes)
Custom css classes can be passed via the loadable component componentCssClasses
input. These will be added to the host element of the provided loadable component. e.g.
app.component.html
<div class="app--emojis"> <loadable-component ... [componentCssClasses]="customCssClasses" > ... </loadable-component> </div>
app.component.ts
@Component({ ... }) export class AppComponent { ... // custom css classes customCssClasses: Array<string> = ['my-custom--class--1', 'my-custom--class--2'] ... }
See the demo and download the source code.
This awesome script developed by dan-harris. Visit their official repository for more information and follow for future updates.