Best way to initialize default values?

Question

typescript

one

export default class App extends Vue {
        private title: string = 'My Vue and CosmosDB Heroes App';

       constructor() {
            super();
        }

2

export default class App extends Vue {
        private title: string;

        constructor() {
            super();
this.title = 'My Vue and CosmosDB Heroes App';
        }

3

export default class App extends Vue {
        private title: string;

        constructor() {
            super();
        }

mounted(){
    this.title = 'My Vue and CosmosDB Heroes App';
}

Which of the options, when and why?

Answer 1

The first case is reactive, the second and third are not. To understand what works and in what order, it is enough to conduct an experiment. Well, or sift through the sources of vue-class-component. Which is easier for you.)