CODEWITHSUNDEEP
htmlangulartypescript
joaoobarreto
joaoobarreto

Reputation: 33

how to check if variable exists in angular?

Here is my example:

      <li class="list-group-item" *ngIf="request.answer.user">
         <a href="" class="d-flex flex-column align-items-center">
           <span class="icofont-law-order icofont-2x"></span>
           <p>user</p>
         </a>
      </li>

I want to show the li only if the variables exists. In some cases, there is no answer.

Upvotes: 0

Views: 2251

Answers (3)

Jose Vicente
Jose Vicente

Reputation: 187

The quick way

<li class="list-group-item" *ngIf="pedido.RecursoTerceiraInstancia.Resposta">
         <a href="" class="d-flex flex-column align-items-center">
           <span class="icofont-law-order icofont-2x"></span>
           <p>Resposta Definitiva</p>
         </a>
</li>

Upvotes: 0

OctavianM
OctavianM

Reputation: 4617

If you go for *ngIf="true ? something : somethingElse" it is pretty obvious that the something will always execute, no matter what (because true is always evaluated to true...)

In your case, you can use the optional chaining operator to make sure the objects exist before accessing properties on them. Your ngIf could look something like this:

 <li class="list-group-item" *ngIf="pedido?.RecursoTerceiraInstancia?.Resposta">

Upvotes: 2

technophyle
technophyle

Reputation: 9128

In Javascript, there's a data type exactly for the purpose of checking if "variable exists": undefined.

So you can do this: typeof pedido.RecursoTerceiraInstancia.Resposta !== 'undefined'

Upvotes: 0

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