How to write ngIf Else Condition Statement in Angular?

Angular 4 updated the *ngIf directive with new feature that allows us to use if/else style syntax as shown below

• Using If

<div *ngIf="isValid">
    If isValid is true
</div>

• Using If with Else

<div *ngIf="isValid;else otherTemplateName">
    If isValid is true
</div>

<ng-template #otherTemplateName>else content displayed...</ng-template>

• Using If with Then and Else

<div *ngIf="isValid; then templateName else otherTemplateName">this text wont show</div>

<ng-template #templateName>If isValid is true</ng-template>
<ng-template #otherTemplateName>else content displayed...</ng-template>

• Using If with Then 

<div *ngIf="isValid; then templateName">this text wont show</div>

<ng-template #templateName>If isValid is true</ng-template>