如何使用"*ngIf else"?

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

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>

2019-08-07 15:08:32

其他回答

在Angular 4.x.x中

你可以用四种方式使用ngIf来实现一个简单的if-else过程:

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>

提示:ngIf对表达式求值，然后呈现then或else 当表达式分别为真或假时，模板在其位置。通常: 那么template就是ngIf的内联模板，除非绑定到不同的值。除非绑定，否则模板为空白。

2017-10-19 15:18:35

"bindEmail"将检查电子邮件是否可用。如果电子邮件存在，则登出将显示。否则将显示Login。

<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>

2017-07-23 13:13:47

你可以使用<ng-container>和<ng-template>来实现:

<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>

你可以在下面找到StackBlitz现场演示:

现场演示

2019-10-24 11:43:32

只需从Angular 8中添加新的更新。

For case if with else, we can use ngIf and ngIfElse. <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> For case if with then, we can use ngIf and ngIfThen. <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> For case if with then and else, we can use ngIf, ngIfThen, and ngIfElse. <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>

2020-01-22 11:03:19