Angular 4 and 5:
using else :
<div *ngIf="isValid;else other_content">
content here ...
</div>
<ng-template #other_content>other content here...</ng-template>
you can also use then else :
<div *ngIf="isValid;then content else other_content">here is ignored</div>
<ng-template #content>content here...</ng-template>
<ng-template #other_content>other content here...</ng-template>
or then alone :
<div *ngIf="isValid;then content"></div>
<ng-template #content>content here...</ng-template>
Demo :
Details:
<ng-template>: is Angular’s own implementation of the <template> tag which is according to MDN :
The HTML
<template>element is a mechanism for holding client-side content that is not to be rendered when a page is loaded but may subsequently be instantiated during runtime using JavaScript.
In Angular 4.x.x You can use ngIf in four way to achieve simple if else procedure:
Just Use If
<div *ngIf="isValid">
If isValid is true
</div>
Using If with Else (Please notice to templateName)
<div *ngIf="isValid; else templateName">
If isValid is true
</div>
<ng-template #templateName>
If isValid is false
</ng-template>
Using If with Then (Please notice to templateName)
<div *ngIf="isValid; then templateName">
Here is never showing
</div>
<ng-template #templateName>
If isValid is true
</ng-template>
Using If with Then and Else
<div *ngIf="isValid; then thenTemplateName else elseTemplateName">
Here is never showing
</div>
<ng-template #thenTemplateName>
If isValid is true
</ng-template>
<ng-template #elseTemplateName>
If isValid is false
</ng-template>
Tip: ngIf evaluates the expression and then renders the then or else template in its place when expression is truthy or falsy respectively. Typically the:
- then template is the inline template of ngIf unless bound to a different value.
- else template is blank unless it is bound.
For Angular 9/8
Source Link with Examples
export class AppComponent {
isDone = true;
}
1) *ngIf
<div *ngIf="isDone">
It's Done!
</div>
<!-- Negation operator-->
<div *ngIf="!isDone">
It's Not Done!
</div>
2) *ngIf and Else
<ng-container *ngIf="isDone; else elseNotDone">
It's Done!
</ng-container>
<ng-template #elseNotDone>
It's Not Done!
</ng-template>
3) *ngIf, Then and Else
<ng-container *ngIf="isDone; then iAmDone; else iAmNotDone">
</ng-container>
<ng-template #iAmDone>
It's Done!
</ng-template>
<ng-template #iAmNotDone>
It's Not Done!
</ng-template>
Just add new updates from Angular 8.
<ng-template [ngIf]="condition" [ngIfElse]="elseBlock">
Content to render when condition is true.
</ng-template>
<ng-template #elseBlock>
Content to render when condition is false.
</ng-template>
<ng-template [ngIf]="condition" [ngIfThen]="thenBlock">
This content is never showing
</ng-template>
<ng-template #thenBlock>
Content to render when condition is true.
</ng-template>
<ng-template [ngIf]="condition" [ngIfThen]="thenBlock" [ngIfElse]="elseBlock">
This content is never showing
</ng-template>
<ng-template #thenBlock>
Content to render when condition is true.
</ng-template>
<ng-template #elseBlock>
Content to render when condition is false.
</ng-template>
Here's some nice and clean syntax on Angular's NgIf and using the else statement. In short, you will declare an ElementRef on an element and then reference it in the else block:
<div *ngIf="isLoggedIn; else loggedOut">
Welcome back, friend.
</div>
<ng-template #loggedOut>
Please friend, login.
</ng-template>
I've taken this example from NgIf, Else, Then which I found to be really well explained.
It also demonstrates using the <ng-template> syntax:
<ng-template [ngIf]="isLoggedIn" [ngIfElse]="loggedOut">
<div>
Welcome back, friend.
</div>
</ng-template>
<ng-template #loggedOut>
<div>
Please friend, login.
</div>
</ng-template>
And also using <ng-container> if that's what you're after:
<ng-container
*ngIf="isLoggedIn; then loggedIn; else loggedOut">
</ng-container>
<ng-template #loggedIn>
<div>
Welcome back, friend.
</div>
</ng-template>
<ng-template #loggedOut>
<div>
Please friend, login.
</div>
</ng-template>
Source is taken from here on Angular's NgIf and Else syntax.
You can Use <ng-container> and <ng-template> for Achieve This
<ng-container *ngIf="isValid; then template1 else template2"></ng-container>
<ng-template #template1>
<div>Template 1 contains</div>
</ng-template>
<ng-template #template2>
<div>Template 2 contains </div>
</ng-template>
You can find the Stackblitz Live demo below
Hope This will helps ... !!!
"bindEmail" it will check email is available or not. if email is exist than Logout will show otherwise Login will show
<li *ngIf="bindEmail;then logout else login"></li>
<ng-template #logout><li><a routerLink="/logout">Logout</a></li></ng-template>
<ng-template #login><li><a routerLink="/login">Login</a></li></ng-template>
ngif expression resulting value won’t just be the boolean true or false
if the expression is just a object, it still evaluate it as truthiness.
if the object is undefined, or non-exist, then ngif will evaluate it as falseness.
common use is if an object loaded, exist, then display the content of this object, otherwise display "loading.......".
<div *ngIf="!object">
Still loading...........
</div>
<div *ngIf="object">
<!-- the content of this object -->
object.info, object.id, object.name ... etc.
</div>
another example:
things = {
car: 'Honda',
shoes: 'Nike',
shirt: 'Tom Ford',
watch: 'Timex'
};
<div *ngIf="things.car; else noCar">
Nice car!
</div>
<ng-template #noCar>
Call a Uber.
</ng-template>
<!-- Nice car ! -->
anthoer example:
<div *ngIf="things.car; let car">
Nice {{ car }}!
</div>
<!-- Nice Honda! -->
<div *ngIf=”condition; else elseBlock”>Truthy condition</div>
<ng-template #elseBlock>Falsy condition</ng-template>
To add then template we just have to bind it to a template explicitly.
<div *ngIf=”condition; then thenBlock else elseBlock”> ... </div>
<ng-template #thenBlock>Then template</ng-template>
<ng-template #elseBlock>Else template</ng-template>
We can simply create a template reference variable [2] and link that to the else condition inside an *ngIf directive
The possible Syntaxes [1] are:
<!-- Only If condition -->
<div *ngIf="condition">...</div>
<!-- or -->
<ng-template [ngIf]="condition"><div>...</div></ng-template>
<!-- If and else conditions -->
<div *ngIf="condition; else elseBlock">...</div>
<!-- or -->
<ng-template #elseBlock>...</ng-template>
<!-- If-then-else -->
<div *ngIf="condition; then thenBlock else elseBlock"></div>
<ng-template #thenBlock>...</ng-template>
<ng-template #elseBlock>...</ng-template>
<!-- If and else conditions (storing condition value locally) -->
<div *ngIf="condition as value; else elseBlock">{{value}}</div>
<ng-template #elseBlock>...</ng-template>
DEMO: https://stackblitz.com/edit/angular-feumnt?embed=1&file=src/app/app.component.html
Sources:
