我使用的是Angular,我想在这个例子中使用*ngIf else(从版本4开始可用):
<div *ngIf="isValid">
content here ...
</div>
<div *ngIf="!isValid">
other content here...
</div>
我怎样才能用ngIf else实现同样的行为?
我使用的是Angular,我想在这个例子中使用*ngIf else(从版本4开始可用):
<div *ngIf="isValid">
content here ...
</div>
<div *ngIf="!isValid">
other content here...
</div>
我怎样才能用ngIf else实现同样的行为?
当前回答
ng-template
<ng-template [ngIf]="condition1" [ngIfElse]="template2">
...
</ng-template>
<ng-template #template2>
...
</ng-template>
其他回答
这里有一些关于Angular的NgIf和使用else语句的漂亮而干净的语法。简而言之,你将在元素上声明一个ElementRef,然后在else块中引用它:
<div *ngIf="isLoggedIn; else loggedOut">
Welcome back, friend.
</div>
<ng-template #loggedOut>
Please friend, login.
</ng-template>
我从NgIf, Else, Then中取了这个例子,我发现这个例子解释得很好。
它还演示了使用<ng-template>语法:
<ng-template [ngIf]="isLoggedIn" [ngIfElse]="loggedOut">
<div>
Welcome back, friend.
</div>
</ng-template>
<ng-template #loggedOut>
<div>
Please friend, login.
</div>
</ng-template>
并且使用<ng-container>如果这是你想要的:
<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来自Angular的NgIf和Else语法。
对于Angular 9/8
源链接及示例
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和Else
<ng-container *ngIf="isDone; else elseNotDone">
It's Done!
</ng-container>
<ng-template #elseNotDone>
It's Not Done!
</ng-template>
3) *ngIf, Then和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>
要使用可观察对象,如果可观察对象数组由数据组成,我通常会这样显示。
<div *ngIf="(observable$ | async) as listOfObject else emptyList">
<div >
....
</div>
</div>
<ng-template #emptyList>
<div >
...
</div>
</ng-template>
在Angular 4、5和6中
我们可以简单地创建一个模板引用变量2,并将其链接到*ngIf指令中的else条件
可能的语法是:
<!-- 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>
演示: https://stackblitz.com/edit/angular-feumnt?embed=1&file=src/app/app.component.html
来源:
NgIf -指令 模板的语法
<div *ngIf="show; else elseBlock">Text to show</div>
<ng-template #elseBlock>Alternate text while primary text is hidden</ng-template>