Service

Create Service

export class CourseService {
    getCourses(): string[] {
        return ["Java J2EE", "NODE JS", ".NET"];
    }
}

Use Service

import {CourseService} from './course.service'

@Component({
    providers: [CourseService]
})
export class CourseComponent {
    courses: string[];

    constructor(courseService: CourseService)
    {
        this.courses = courseService.getCourses();
    }
}