What is the best way to activate an alert or swal function just once instead of repeatedly?

Question

What is the best way to activate an alert or swal function just once instead of repeatedly?

I am just starting to learn Angular.

Currently, I have an application that contains two variables related to the status of financial transactions. These variables are: tab1TrxMessage, which holds any important messages, and tab1TrxStatus that indicates whether a transaction has Failed, is successful, or is in pending status. In case of a failed transaction, I want the user to receive a swal alert/notification like the one below:

swal({
       title:'Error!',
       text: 'Warning... Transaction failed!',
       type: 'error',
       confirmButtonText: 'Ok',
       confirmButtonColor: '#ff754f'
     });

My current code snippet looks like this:

../component.html

<div class="sign-btn text-center">
  <a class="btn btn-lg text-white">
    <span *ngIf="tab1TrxMessage">{{tab1TrxMessage}}</span>
    <span *ngIf="!tab1TrxMessage && tab1TrxStatus != 'Success'">Failed</span>
    <span *ngIf="transactionFailed()">Failed</span>
  </a>
</div>

Focusing on the transactionFailed() function...

../component.ts

public transactionFailed() {

    if(this.tab1TrxMessage == 'Failed: Cancelled by User' && this.tab1TrxStatus != 'Success') {

        console.log("You are in transactionFailed!")

        swal({
           title:'Error!',
           text: 'Warning... Transaction failed!',
           type: 'error',
           confirmButtonText: 'Ok',
           confirmButtonColor: '#ff754f'
         });

         return true;
    }

    return false;
}

After a failed transaction using the above code, the message You are in transactionFailed! appears multiple times in the browser console...

https://i.sstatic.net/Qs7Od.png

...and the swal alert with Warning... Transaction failed! keeps popping up repeatedly. This situation leads me to wonder if there's a better way to ensure that the swal alert displays only ONCE per failed transaction?

I would appreciate your suggestions and guidance.

javascript angular typescript

Answer 1

Answer №1

Create a mechanism to ensure that your code runs only once, like a counter.

failedTransactionCntr = 0;
public transactionFailed() {

    if(this.tab1TrxMessage == 'Failed: Cancelled by User' && this.tab1TrxStatus != 'Success') {

        console.log("You are in transactionFailed!")
        if (this.failedTransactionCntr == 0) {
          swal({
           title:'Error!',
           text: 'Warning... Transaction failed!',
           type: 'error',
           confirmButtonText: 'Ok',
           confirmButtonColor: '#ff754f'
         });
         this.failedTransactionCntr ++;
        }
         return true;
    }

    return false;
}

Answer 2

Create a mechanism to ensure that your code runs only once, like a counter.

failedTransactionCntr = 0;
public transactionFailed() {

    if(this.tab1TrxMessage == 'Failed: Cancelled by User' && this.tab1TrxStatus != 'Success') {

        console.log("You are in transactionFailed!")
        if (this.failedTransactionCntr == 0) {
          swal({
           title:'Error!',
           text: 'Warning... Transaction failed!',
           type: 'error',
           confirmButtonText: 'Ok',
           confirmButtonColor: '#ff754f'
         });
         this.failedTransactionCntr ++;
        }
         return true;
    }

    return false;
}

Answer 3

Answer №2

When it comes to the way Angular detects changes, the transactionFailed() function is triggered during each change detection cycle due to your specified strategy and method. This is necessary because updating the DOM is a crucial aspect of change detection in Angular, requiring the invocation of transactionFailed() to determine the appropriate value for DOM updates.

To prevent multiple calls to transactionFailed(), consider changing the changeDetectionStrategy to onPush:

@Component({
 selector: 'your-component',
 templateUrl: './your.component.html',
 styleUrls: ['./your.component.css'],
 changeDetection: ChangeDetectionStrategy.OnPush // this line
})

export class YourComponent {

}

However, keep in mind that you may need to manually trigger change detection by calling the detectChanges() method:

constructor(private ref: ChangeDetectorRef) {
    this.ref.detach();
}

start() {
    this.fooVariable = 'This is a foo vaiable';
     this.ref.detectChanges();
}

For more information on Change detection strategies, refer to this article

Answer 4

When it comes to the way Angular detects changes, the transactionFailed() function is triggered during each change detection cycle due to your specified strategy and method. This is necessary because updating the DOM is a crucial aspect of change detection in Angular, requiring the invocation of transactionFailed() to determine the appropriate value for DOM updates.

To prevent multiple calls to transactionFailed(), consider changing the changeDetectionStrategy to onPush:

@Component({
 selector: 'your-component',
 templateUrl: './your.component.html',
 styleUrls: ['./your.component.css'],
 changeDetection: ChangeDetectionStrategy.OnPush // this line
})

export class YourComponent {

}

However, keep in mind that you may need to manually trigger change detection by calling the detectChanges() method:

constructor(private ref: ChangeDetectorRef) {
    this.ref.detach();
}

start() {
    this.fooVariable = 'This is a foo vaiable';
     this.ref.detectChanges();
}

For more information on Change detection strategies, refer to this article

Answer 5

Answer №3

If you want to ensure it is only valid once, consider using a flag variable. For instance:

let transactionFlag = false; 
public transactionFailed() {

    if(this.tab1TrxMessage == 'Failed: Cancelled by User' && this.tab1TrxStatus != 'Success' && !transactionFlag) { 

        console.log("You are in transactionFailed!")
        transactionFlag = true;
        swal({
           title:'Error!',
           text: 'Warning... Transaction failed!',
           type: 'error',
           confirmButtonText: 'Ok',
           confirmButtonColor: '#ff754f'
         });

         return true;
    }

    return false;
}

Answer 6

If you want to ensure it is only valid once, consider using a flag variable. For instance:

let transactionFlag = false; 
public transactionFailed() {

    if(this.tab1TrxMessage == 'Failed: Cancelled by User' && this.tab1TrxStatus != 'Success' && !transactionFlag) { 

        console.log("You are in transactionFailed!")
        transactionFlag = true;
        swal({
           title:'Error!',
           text: 'Warning... Transaction failed!',
           type: 'error',
           confirmButtonText: 'Ok',
           confirmButtonColor: '#ff754f'
         });

         return true;
    }

    return false;
}

What is the best way to activate an alert or swal function just once instead of repeatedly?

Answer №1

Answer №2

Answer №3

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