Callback functions in TypeScript

Question

I'm just getting started with Angular 2 and TypeScript and I can't seem to figure out how to use callback functions, I know this may be a silly question but given this regular javascript code:

someOnject.doSomething('dsadsaks', function(data){
      console.log(data);
});

What is the equivalent in TypeScript?

score 6 · Accepted Answer · answered Feb 20 '16 at 20:04

6

The same code works in TypeScript. Alternatively you can use

someOnject.doSomething('dsadsaks', data => {
  console.log(data);
});

The difference is that in the 2nd version this. would refer to the class surrounding the code.

answered Feb 20 '16 at 20:04

Günter Zöchbauer

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hey you mean if `this` will refer to class variable or function variable ?? – Nauman Ahmad Jul 12 '17 at 18:11
@NaumanAhmad sorry, I don't understand what you mean. `this` refers to the class. I'm not dure myself what I referred to with this sentence ; – Günter Zöchbauer Jul 12 '17 at 19:05
thanks i was just asking if `this` when used in above callback function will it refer to class or call back function ? – Nauman Ahmad Jul 12 '17 at 19:55
1

To the class. . – Günter Zöchbauer Jul 12 '17 at 20:00

agconti · Answer 2 · 2016-02-20T20:12:19.337

4

Your example is perfectly valid in a TypeScript project. If you wanted you could also strongly type your inputs:

const msg:string = 'dsadsaks'
someOnject.doSomething(msg, data:string =>{
      console.log(data);
});

edited Feb 20 '16 at 20:12

answered Feb 20 '16 at 20:05

agconti

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Callback functions in TypeScript

2 Answers2