How to use Kotlin to generate a javascript function `constructor`?

Question

I want to use Kotlin to generate some JavaScript like following:

function MyComponent() {
    self.constructor = function() {}
}

The problem is constructor is a keyword in Kotlin, I can't just write like:

class MyComponent {
  fun constructor() {}
}

I also tried:

class MyComponent {
    @JsName("constructor")
    fun ctor() {}
}

It still report errors like:

JavaScript name generated for this declaration clashes 
with built-in declaration {1}

How to generate a javascript function which has name constructor?

I know it's not really solving your problem, but maybe just try changing the letter 'c' to uppercase? ... Just a suggestion... — JO3-W3B-D3V
– JO3-W3B-D3V, Commented Apr 3, 2018 at 14:52
@JO3-W3B-D3V The constructor name is required by the js lib used with kotlin, can't be changed — Freewind
– Freewind, Commented Apr 3, 2018 at 14:59
I see your problem, I've never used kotlin personally, I've been meaning to, however, I've never actually used it, JS on the other hand... have you tried something like window["constructor"] within your JS? I'm not sure if that would work or not... — JO3-W3B-D3V
– JO3-W3B-D3V, Commented Apr 3, 2018 at 15:04
No problem at all, I hope it works fine for you. I think it may work due tot he way it's been written, I may be wrong, who knows. Let me know if it works or not? :) — JO3-W3B-D3V
– JO3-W3B-D3V, Commented Apr 3, 2018 at 15:20

Anton Bannykh · Accepted Answer · 2018-04-03 17:56:33Z

3

There should be no problem with the top-level functions. The fun constructor() {} should just work, yielding function constructor(){}. At least that's what it does in Kotlin 1.2.31.

On the other hand member functions named constructor are prohibited (e.g. you cannot get A.prototype.constructor = function () {} in the output js file). For one thing that would ruin the is-check implementation.

Modifying the constructor property inside the class constructor should be possible:

// Kotlin
class A {
  init{
    this.asDynamic().constructor = fun(a: Int) { println(a) }
  }
}

// JS
function A() {
  this.constructor = A_init$lambda;
}
function A_init$lambda(a) {
  println(a);
}

Hope that helped.

edited Apr 3, 2018 at 17:56

answered Apr 3, 2018 at 15:25

Anton Bannykh

1545 bronze badges

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

6 Comments

JO3-W3B-D3V Over a year ago

You say it should just work? - This isn't really useful feedback? I personally don't use Kotlin myself, but as I said, could he not just do something like window["constructor"]? Again, I wouldn't know, I know JS, Kotlin, not so much.

Freewind Over a year ago

@anton Yes, you are right if fun constructor is at top level, thanks! Actually I simplified my problem too hard, my real problem is the constructor inside a class. Let me modify the question

Anton Bannykh Over a year ago

@Freewind It is possible to modify the property inside the class constructor (added to the answer). Is that what you want?

Anton Bannykh Over a year ago

@JO3-W3B-D3V I was being polite. No, window["constructor"] is not the solution, because a) it solves the problem that doesn't exist, and b) window is not defined in some environments (e.g. NodeJs)

Anton Bannykh Over a year ago

@Freewind by the way, could you tell what exactly that library uses the constructor property for?

|

Collectives™ on Stack Overflow

How to use Kotlin to generate a javascript function `constructor`?

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related