Typescript: this inside parameters of arrow function

Question

I'm familiar with the behaviour of this inside an arrow function in typescript (or at least I thought so). However today I stumbled across a this being used in the arguments list of an arrow function (this is from the type definitions of the alexa-sdk):

export interface Handlers<T> {
    [intent: string]: (this: Handler<T>) => void;
}

What does this actually mean and how would I implement this?

let handlers: Handlers<IntentRequest> = {
    "MyIntent" = ???
}

I know that I can do something like:

let handlers: Handlers<IntentRequest> = {
        "MyIntent" = function() {
           let self: Alexa.Handler<IntentRequest> = this;
        }
}

but is there a more elegant solution without the self/this assignment with a arrow function?

You should check this parameters section here: typescriptlang.org/docs/handbook/functions.html — Amid
– Amid, Commented Aug 24, 2017 at 7:20

Titian Cernicova-Dragomir · Accepted Answer · 2017-08-24 07:31:39Z

2

In newer versions of typescript you can specify the type of this as a pseudo paramter to the function

let handlers: Handlers<IntentRequest> = {
    "MyIntent": function (this: Handlers<IntentRequest> /* , realParam: string */) {
       // this will have the type Handlers<IntentRequest>
    }
}

answered Aug 24, 2017 at 7:31

Titian Cernicova-Dragomir

253k37 gold badges465 silver badges395 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Typescript: this inside parameters of arrow function

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related