Angular2 Typescript how to refactor code out of Component constructor

Question

The Angular 2 guide has this example with a constructor in a

component://Typescript
class DisplayComponent {
  myName: string;
  names: Array<string>;
  constructor() {
    this.myName = "Alice";
    this.names = ["Aarav", "Martín", "Shannon", "Ariana", "Kai"];
  }
}

From https://angular.io/docs/ts/latest/guide/displaying-data.html#Create-an-array (retrieved 2015-10-30)

Consider this is a simple example, but often in real life, my constructors grow bigger and bigger. Also I have sometimes the need to use the same logic several places, and not only on construction time.

My first reaction was to create a separate function and call that on the instance. But Typescript does not allow this, since the instance is not created when the constructor runs.

My question is: How do I extract lines of code from the constructor and pull it out into a separate function?

You can create a instance function and call it from the constructor. Maybe i am not getting what you meant here. — Chandermani
– Chandermani, Commented Oct 30, 2015 at 13:18
@Chandermani please add an example as an answer. What you describe is exactly what I am looking for :) — Jesper Rønn-Jensen
– Jesper Rønn-Jensen, Commented Oct 30, 2015 at 13:47

Bruno Grieder · Accepted Answer · 2015-10-30 14:02:49Z

2

Is this what you are looking for ?

class MyClass {

    constructor( ) {
        MyClass.saySomething()
        this.sayItAll()
    }

    public static saySomething(){
        console.log('Hi')
    }

    public sayItAll(){
         console.log('Hello')
         MyClass.saySomething()
    }
}

So you can also call MyClass.saySomething() from an other class without an instance of MyClass ?

edited Oct 30, 2015 at 14:02

answered Oct 30, 2015 at 13:40

Bruno Grieder

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2 Comments

Jesper Rønn-Jensen Over a year ago

yes, this is an example of calling a static method. Can you also update the example with an instance example (since I want to write properties on the instance).

Bruno Grieder Over a year ago

Obviously you need to get an instance of MyClass to call the method sayItAll()

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