Angular io (4) *ngFor first and last
Inside the ngFor
you have access to several variables:
- index: number: The index of the current item in the iterable.
- first: boolean: True when the item is the first item in the iterable.
- last: boolean: True when the item is the last item in the iterable.
- even: boolean: True when the item has an even index in the iterable.
- odd: boolean: True when the item has an odd index in the iterable.
So:
<md-expansion-panel *ngFor="let item of items; first as isFirst"
*ngClass="{ 'first' : isFirst }">
<content></content>
</md-expansion-panel>
Documentation at https://angular.io/api/common/NgForOf gives this example:
<li *ngFor="let user of userObservable | async as users; index as i; first as isFirst">
{{i}}/{{users.length}}. {{user}} <span *ngIf="isFirst">default</span>
</li>
This how you can do it :
<md-expansion-panel
*ngFor="let item of items; let first = first; let last = last"
[ngClass]="{ 'first' : first }">
<content></content>
</md-expansion-panel>
NgFor provides several exported values that can be aliased to local variables:
index
will be set to the current loop iteration for each template context so it start from 0.first
will be set to a boolean value indicating whether the item is the first one in the iteration.last
will be set to a boolean value indicating whether the item is the last one in the iteration.even
will be set to a boolean value indicating whether this item has an even index.odd
will be set to a boolean value indicating whether this item has an odd index.
for more information : NgFor-directive ðð
a complete example
<div
*ngFor="let n of items; let itemsCount = count;let idx = index , let isOdd = odd;let first = first ;let last = last;">
{{n}} ,
{{itemsCount}} ,
{{idx}} ,
odd ð {{isOdd}} ,
first ð {{first}} ,
last ð {{last}}
</div>
demo ð