form validation in angular 8 code example
Example 1: angular html input validation template driven
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<input id="name" name="name" class="form-control"
required minlength="4" appForbiddenName="bob"
[(ngModel)]="hero.name"
<div *ngIf="name.invalid && (name.dirty || name.touched)"
class="alert alert-danger">
<div *ngIf="name.errors.required">
Name is required.
</div>
<div *ngIf="name.errors.minlength">
Name must be at least 4 characters long.
</div>
<div *ngIf="name.errors.forbiddenName">
Name cannot be Bob.
</div>
</div>
Example 2: ng2 validations angular using reactiveforms
<form [formGroup]="form">
<input type="password" formControlName="password"/>
<p *ngIf="form.controls.password.errors?.required">required error</p>
<input type="password" formControlName="certainPassword"/>
<p *ngIf="form.controls.certainPassword.errors?.equalTo">equalTo error</p>
</form>