Angular Directives List tutorial with examples

we are going to learn about different types of built-in directives in angular.

Contents

• ngIf

• ngFor

• ngModel

• ngClass

• ngStyle

ngIf

ngIf directive helps us to add or remove HTML elements conditionally into the dom.

Example:

<h1 *ngIf="isActive">Im happy</h1>

In the above code, we have added *ngIf=”isActive” so that h1 element will only render into the dom if isActive property is true.

ngFor

ngFor directive helps us to loop over the array of items and render each item into the dom.

Example:

<ul>   <li  ngFor="let user of users">{{user}}</li></ul>

Here we added a ngFor=”let user of users” where users is an array we are looping, on each iteration user variable, is pointing to the different user present in the array.

ngModel

ngModel helps us to do two-way data binding in angular it means we can sync the data in both directions.

To use ngModel directive first we need to import the FormsModule inside our app.module.ts file and add it to the imports array.

import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { FormsModule } from '@angular/forms';import { AppComponent } from './app.component';@NgModule({  declarations: [    AppComponent  ],  imports: [    BrowserModule,    FormsModule  ],  providers: [],  bootstrap: [AppComponent]})export class AppModule { }

Using ngModel directive

<input [(ngModel)]="hello" />

In the above code, we have added [(ngModel)] = “hello” to input element where hello property bindsto the input value in both directions.

ngClass

ngClass directive helps us to add or remove CSS class names dynamically based on a particular condition.

Example:

<h1 [ngClass]="[isActive ? 'red' : 'green']">Hello angular</h1>

In the above code, we have added [isActive ? ‘red’ : ‘green’] to ngClass directive where isActiveis an expression and red,green are css class names.

If isActive is true red class is added to h1 element otherwise green class is added.

ngStyle

ngStyle directive helps us to set inline styles to HTML elements.

Example:

<h1 [ngStyle]="{'background-color': mycolor}">Hello angular</h1>

Here we have added an object {‘background-color’: mycolor} to ngStyle directive where background-color is a CSS style name and mycolor is a JavaScript expression to be evaluated.