Angular - What is the best way to pass the value of a variable that is declared within a component over to a service file?

Is there a way to access a variable declared inside a component in an Angular service file? I tried searching online but couldn't find a solution that fits my needs.

mylib.component.ts

import { Component, Input } from '@angular/core';

@Component({
  selector: 'srr-mylib',
  template: `
    <h1> {{counter}} </h1>
    <button class="btn btn-primary" (click)=counterIncrease()>Increase</button>
  `,
  styles: [
  ]
})
export class MylibComponent implements OnInit {

  counter: number = 0   // the variable I want to access in the service file
  constructor( ) {}

  ngOnInit(){
   
  }

  counterIncrese() {
    this.counter = this.counter + 1;
  }
  
}

mylib.service.ts

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class MylibService { 

  constructor() { }

  getCounter(){
    //Function that needs to use the 'counter' variable
  }
}

Answer №1

Traditionally, when handling a variable that needs to be accessible in both a service and a component, it is recommended to declare the variable in the service and then import the service into the component:

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class MylibService { 

counter: number = 0   // This is the variable

  constructor() { }

}
import { Component, Input } from '@angular/core';

//import { MylibService } from 'path to the service'

@Component({
  selector: 'srr-mylib',
  template: `
    <h1> {{this.service.counter}} </h1>  <!--use it in your page-->
    <button class="btn btn-primary" (click)=counterIncrease()>Increase</button>
  `,
  styles: [
  ]
})
export class MylibComponent implements OnInit {

  counter: number = 0   // This is the variable

  constructor(private service: MylibService) {} // Import the service

  ngOnInit(){
   
  }
  counterIncrease() {
    this.service.counter++; // Set it
  }
  
}

By declaring the variable in the service, you can easily modify and access it in both the service and the component, as well as in the template. If you increase the counter via the button, the changes will be reflected in the service and consequently in the component.

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