Get column value onClick in nested HTML Table [Javascript]

Question

I have a nested HTML table which expands on click. When I click inner row, I would like to get column value. Right now, I am getting the column value on click of outer row. For instance in the below image, when I click coding/testing, I would like to pass an alert as "Place". Right now, I get alert as "place" when I click city.

Component:

 trigger(){
  var table: any = document.getElementById("table");
  var rows = table.rows;
  for (var i = 0; i < rows.length; i++) {
  rows[i].onclick = (function (e) {
    var j = 0;
    var td = e.target;
    while( (td = td.previousElementSibling) != null ) 
        j++;
    alert(rows[0].cells[j].innerHTML);
 });
 }
 }

Demo

Answer 1

You don't need any DOM manipulation, you can simplify your solution as below:

app.component.ts

// .......
export class AppComponent {
  trigger(columnName: string) {
    alert(columnName);
  }
// .......
}

app.component.html

<table class="table table-hover table-bordered table-responsive-xl" id="table">
    <tr>
        <td> Name </td>
        <td> Place </td>
        <td> Phone </td>
    </tr>

    <tbody>

        <ng-container *ngFor="let data of data1">
            <tr (click)="data.expanded = !data.expanded">
                <td (click)="trigger('Name outer')"> {{ data.expanded ? '&ndash;' : '+'}} {{data.name}} </td>
                <td (click)="trigger('Place outer')"> {{data.place}} </td>
                <td (click)="trigger('Phone outer')"> {{data.phone}} </td>
                <td (click)="trigger('Hobbies Outer')"> {{data.hobbies}} </td>
                <td (click)="trigger('Profession outer')"> {{data.profession}} </td>
            </tr>

            <ng-container *ngIf="data.expanded">
                <tr *ngFor="let data of findDetails(data)">
                    <td style="padding-left: 12px" (click)="trigger('Name inner')"> {{data.datades.name}} </td>
                    <td (click)="trigger('Hobbies inner')"> {{data.datades.hobbies}} </td>
                    <td (click)="trigger('Profession inner')"> {{data.datades.profession}} </td>
                </tr>
            </ng-container>
        </ng-container>
    </tbody>
</table>

Answer 2

I'm not sure why you have this code in your trigger function. But, if you need to get the column name when a data cell is clicked, you can use the following approach.

1. Inject into your trigger function call a current event object and your header row element template variable :

<table class="table table-hover table-bordered table-responsive-xl" id="table">
    <tr #header>
    </tr>
    <tbody>
        <ng-container *ngFor="let data of data1">
            <ng-container *ngIf="data.expanded">
                <tr *ngFor="let data of findDetails(data)" (click)="trigger($event, header)">
                </tr>
            </ng-container>
        </ng-container>
    </tbody>
</table>

So, #header name is assigned to the first tr element and then it's passed along with $event to the trigger function.

2. In your trigger function, consume these two parameters. $event will be a regular MouseEvent object and header will be a regular tr element. After this, you can find the clicked column header by the clicked cell index in your row. gsnedders in the StackOverflow thread provided a solution for how to find the element index inside its parent. Your trigger function may look like:

trigger($event, header) {
  const index = this.getChildNumber($event.target);
  alert(header.childNodes[index].textContent.trim());
}

This StackBlitz project illustrates this approach.