Clicking on a button in the Angular framework results in a change

I am faced with a scenario where an input value is received from another component:

    <input [value]="myInput.something">
    <span (click)="incrementPlus()">+</span>

What I need is a straightforward function that can increment the input value by a specified number each time it's clicked. The challenge here is that the input value is provided through:
@Input() myInput: number;
Without creating multiple variables to store and reuse the value across different inputs, I'm looking for a clean solution. I could easily modify the @Input within the function, save it in a variable, and then bind the variable to the HTML input value. However, this approach would result in numerous variables being created for each input, which doesn't align with best practices.

This dilemma differs from others I have come across, as they typically involve static value changes or using intermediary variables — something I aim to avoid.

Answer №1

If you wish to update the value within the parent components as well, you'll need to utilize @Output and two-way binding. When there is a change in the input, you will invoke the emit method of the output EventEmitter to inform the parent that the value has been altered.

For two-way binding, the output should be named similarly to your input, with the addition of Change.

In the child component, you would include:

@Input() something: number;
@Output() somethingChange = new EventEmitter<number>();

And in the parent component:

[(something)]="theValue"

Subsequently, when you use somethingChange.emit to send a value, it updates the parent's value, which then gets passed down to the child component as well.

Here is a detailed example: https://stackblitz.com/edit/angular-en58l5?file=src%2Fapp%2Fhello.component.ts

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