ng-alt

NgAlt

An Angular directive used the same way as @NgSwitch except that it only renders the first truthy directive in the group :

<div ngAltGroup>
  <span *ngAlt="false">A</span>
  <span *ngAlt="true">B</span>
  <span *ngAlt="true">C</span>
</div>

This will render :

<div>
  <span>B</span>
</div>

Exemple with form errors:

  <mat-input-container>
    <input matInput formControlName="password">
    <mat-error ngAltGroup>
      <span *ngAlt="form.controls.email.hasError('required')">Must not be empty</span>
      <span *ngAlt="form.controls.email.hasError('minLength')" translate>Must be at least 8 chars long</span>
      <span *ngAlt="form.controls.email.hasError('invalid')" translate>Must be contain symbols, digits and mixed upper and lower cased letters</span>
    </mat-error>
  </mat-input-container>

This will render the first truthy error only in order of appearance.

Installation

  npm install --save ng-alt

  # or

  yarn add ng-alt

Usage

Import the module in any Angular module you want to use the directive :

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { NgAltModule } from 'ng-alt';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    NgAltModule, // <--- add the module here
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Use it as above :

• Wrap all alternatives in an element with the [ngAltGroup] directive.
• Add the [ngAlt] directive to every element to be conditionally rendered (order matters).