super() not calling parent's constructor on IE9

Hello,

After upgrading to babel@6.0.14, babelify@7.1.0 and babel-preset-es2015@ 6.0.14 it seems that on IE9, calling super() on a child class’ constructor doesn’t call the parent’s constructor anymore.

The two classes live on different files and I import/export the whole using the ES2015 module syntax.

Like so:

// in myClassA.js
export class A {
    constructor() {
        console.log('I am your father');
    }

    init() {
        console.log('And I know who your sister is');
    }
}

// in myClassB.js
import {A} from './myClassA.js';

export class B extends A {
    constructor() {
        // Won't do anything
        super();
    }

    init() {
        // Will fire A.init() properly: 'And I know who your sister is' is logged
        super.init();
    }
}

// Wherever else
import {B} from './myClassB';

window.onload = () => {
    var B = new B();
}

And in my gulp task:

(...).transform(babel.configure({
    presets: ["es2015"],
    ignore: ["client/vendor"]
}));

It’s working well on IE >= 10 but unfortunately not on IE9. I’m opening the issue on the babelify repo since I’m using it but maybe it belongs to the babel one.

Reverting back to babel@5 and babelify@6 fixes the issue.

Thanks for the support and continue the good work guys !

[rxaviers]

Please, what’s the final word on this? It seems like super doesn’t work on <=IE10 except if using es2015-loose preset. Is that correct? Is that the suggested approach/workaround or is there a better solution that doesn’t make use of the loose mode (e.g., inclusion of a polyfill?)? Should http://babeljs.io/docs/plugins/transform-es2015-object-super/ include a list of supported browsers? Thank you

[peternoordijk]

Is this still an issue? I tried to run a few tests and I didn’t encounter any problems anymore on IE9. I used the es2015-loose preset without transform-proto-to-assign. My code is in here: https://jsfiddle.net/peternoordijk/ymtyud9y/