Typescript: Calling a "method" of another class

Question

I'm pretty new to java-/type-script and I've some troubles grasping their concepts. I would like to call a method of another class. However, I've been unsuccessful so far.

export class Foo {
   calcSomeThing(parameter:number): number {
      //stuff
   }
}

class Bar {
   var foo:Foo = new Foo();

   calcOtherThing() {
      result = foo.calcSomething(parameter)
   }
}

What is the correct way to call calcSomething on foo from calcOtherThing?

---

edit: added an instance of foo

Answer 1

There are several problems with your code.

1. Typescript is case sensitive. So "calcSomething" and "calcSomeThing" are two different methods.
2. The only way to access cals methods and properties is through "this" keyword: this.foo
3. To define class property use private/protected/public modifier. Or no modifier at all (that will be the same as public). So no things like "var foo" in the class body.

Taking this into account the fixed code would look like this:

export class Foo 
{
    calcSomeThing(parameter:number): number 
    {
        //Stuff
    }
}

class Bar 
{
    private foo:Foo = new Foo();

    calcOtherThing(parameter: number): number 
    {
            return this.foo.calcSomeThing(parameter)
    }
}

Answer 2

calcSomeThing is a non-static method/function. Create an instance of Foo to be able to call it:

let foo:Foo = new Foo();
let result:number = foo.calcSomeThing( parameter );

Never use var in Typescript - let is your friend.

Answer 3

I believe you need a constructor for classes in TypeScript. In the example I provide I made mine data holders, but it's not required. Additionally, your calculation functions need to return values. Also, in order to use Foo in an instance of Bar, you need to make an instance of Foo.

class Foo {
   private data; 
   constructor(data: number) {
       this.data = data;
   }

   calcSomeThing(parameter:number): number {
      return parameter + 1;
   }
}

class Bar {
   private data;
   private foo:Foo = new Foo(3);

   constructor(data: number) {
       this.data = data;
   };

   calcOtherThing(): number {
      let result = this.foo.calcSomeThing(this.data);
      return result;     
   }
}

let bar = new Bar(5);
console.log(bar.calcOtherThing()); // returns 6