How to assign one strict datatype variable value using another variable in angular?

Question

I am an Angular Developer and working on one project in which I used strict DataType and define variable with my custom DataType Like this :

Code: 1 | 2 | 3 | 4 | 5 = 1;

Here above variable declaration will work perfect if we assign this code variable with constant value directly. like this :

Code = 3;

But this will give an Error if I try to assign it using a variable like this :

let num = this.getNumberBewteen1_5();
Code = num;

and function getNumberBewteen1_5() is the function which return one number between 1 and 5 ;

Is there any way to fix it without remove strict DataType in angular ?

Answer 1

The problem is that method returned type should be the same as variable type.
You try to assign number to 1 | 2 | 3 | 4 | 5 which is different type.

Working example:

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

type YourType = 1 | 2 | 3;

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  a: YourType;

  constructor() {
    let b = this.yourMethod();
    this.a = b;
  }

  yourMethod(): YourType { // returned type is YourType (not number)
    return 1; // or 2 | 3
  }
}