How to show/hide in Angular2 - html

Question

I have a component that show/hide element by clicking a button.
This is my html
<div *ngFor="let history of histories | sortdate: '-dateModified'">
<p><b>{{ history.remarks }}</b> - <i>{{history.dateModified | date:'short'}}</i></p>
<a href="google.com"
[class.datatable-icon-right]="history.$$expanded"
[class.datatable-icon-down]="!history.$$expanded"
title="Expand/Collapse Row"
(click)="toggleExpandRow(history)"></a>
<!-- hide/show this by clicking the button above.-->
<div *ngFor="let step of history.steps; let i = index">
<b>{{i+1}}.</b> {{step}}
<span class="clear"></span>
</div>
<hr />
</div>
and my .ts
toggleExpandRow(row) {
console.log('Toggled Expand Row!', row);
//row
return false;
}
trying to search but, can't find any same sample.
On jquery, I can do this, but on Angular2, I am having hard time to figure this.

Answer 1

There are two options:
1- You can use the hidden directive to show or hide any element
<div [hidden]="!edited" class="alert alert-success box-msg" role="alert">
<strong>List Saved!</strong> Your changes has been saved.
</div>
2- You can use the ngIf control directive to add or remove the element. This is different of the hidden directive because it does not show / hide the element, but it add / remove from the DOM. You can loose unsaved data of the element. It can be the better choice for an edit component that is cancelled.
<div *ngIf="edited" class="alert alert-success box-msg" role="alert">
<strong>List Saved!</strong> Your changes has been saved.
</div>

Answer 2

Use the ngIf in your repeated rows. Create a boolean property called showStep to indicate whether the row should be expanded or not.
<div *ngFor="let step of history.steps; let i = index" ngIf="history.showStep">
<b>{{i+1}}.</b> {{step}}
<span class="clear"></span>
</div>
Then, in your .ts file:
toggleExpandRow(history) {
history.showStep = !history.showStep
//note the same porperty of showStep that is used in your html
}
Extra:
In fact, to save a few lines of codes, you don't even need the toggleExpandRow function at all. You can do it inline in your html:
//other attributes omitted for brevity
<a (click)="history.showStep = !history.showStep">