Adding Javascript or importing js file into Angular 9 component

Question

I'm new to Angular and creating a project that that uses routing. I'd like to import a js file from src/assets/js/custom.js

I've created a service that imports an injectable like so

test.service.ts

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

@Injectable()
export class TestService {
    testFunction() {
      console.log('Test');
    }
}

home.compontents.ts looks like

import { Component, OnInit } from '@angular/core';
import { Router } from '@angular/router';
import { TestService } from './test.service';

declare var require: any

@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.scss'],
  providers: [TestService]

})

export class HomeComponent implements OnInit {

  constructor() {private testService: TestService}

  ngOnInit(): void {
    this.testService.testFunction();

  }

}

But I am getting the following error

17   constructor() {private testService: TestService}
                    ~~~~~~~
src/app/home/home.component.ts:19:13 - error TS1005: ';' expected.

19   ngOnInit(): void {
               ~
src/app/home/home.component.ts:20:9 - error TS1005: ':' expected.

20     this.testService.testFunction();
           ~
src/app/home/home.component.ts:20:36 - error TS1005: ',' expected.

20     this.testService.testFunction();
                                      ~
src/app/home/home.component.ts:24:1 - error TS1128: Declaration or statement expected.

24 }
   ~

I've tried so many different ways from Google searches and not coming up with anything. Can anyone please help?

UPDATE

Thanks for the updates, I've updated the constructor, however I am getting an error

ERROR in src/app/home/home.component.ts:3:29 - error TS2307: Cannot find module './test.service' or its corresponding type declarations.

3 import { TestService } from './test.service';

I'm not sure if I am going the right way with this. Each component I am using has 1 or 2 js files that I need to import. What would be the best way to do this?

Answer 1

A service passed as a parameter in class constructor to be injected as a dependency.

constructor(private testService: TestService) {}

Answer 2

The constructor is written incorrectly. Please write it as given below

 constructor(private testService: TestService) {}

Also, you have given service as @Injectable() ,then you have to define the service in app.module.ts file. Alternatively, you can give

@Injectable({
  providedIn: 'root'
})

This will eliminate adding the service in providers.

Answer 3

home.compontents.ts constructor should be like below:

constructor(private testService: TestService) {}