Unnamed default exports don't work with `--t es6 --m commonjs`

[joeduffy]

Compiling the following code:

"use strict";
export default class {};

Using the command line tsc --t es6 --m commonjs produces illegal JavaScript:

"use strict";
class {
}
exports.default = default_1
;

I realize this is a weird combination of switches, however it seems necessary to target current versions of Node.js/V8 that don't yet natively support ES6 modules.

[weswigham]

This conditional needs to be updated to emit the temp name if the class is an exported default class when not targeting ES6. Forgot about unnamed classes when adding tests in #5648.

While looking at it, it would probably also be a good idea to verify all of the default export results with functions and unnamed function expressions as well...

[vvakame]

same as unnamed function.

$ tsc -v
Version 1.8.0-dev.20151130
$ cat sub.ts
export default function (name: string) {
    return `Hi! ${name}`;
}
$ tsc --target es6 --module commonjs sub.ts
$ cat "use strict";
function (name) {
    return `Hi! ${name}`;
}
exports.default = default_1;

[nmalaguti]

Actually, I may have misunderstood the expected behavior for TypeScript 1.7 when targeting commonjs with ES6 modules.

This also appears to be a problem with named classes that are default exports.

$ tsc -v
message TS6029: Version 1.7.3

example.ts

// example.ts
export default class Example {
    public get() {
        return 1;
    }
}

subExample.ts

// subExample.ts
import Example from "./example";

export default class SubExample extends Example {
    public get() {
        return 3;
    }

    public foo() {
        return 2;
    }
}

$ tsc -t es6 -m commonjs example.ts subExample.ts

example.js

// example.js
class Example {
    get() {
        return 1;
    }
}
exports.Example = Example;

subExample.js

// subExample.js
var example_1 = require("./example");
class SubExample extends example_1.default {
    get() {
        return 3;
    }
    foo() {
        return 2;
    }
}
exports.SubExample = SubExample;

When run with node v5:

TypeError: Class extends value undefined is not a function or null
    at Object.<anonymous> (subExample.js:3:35)

[weswigham]

That last bit duplicates #5594 and should be fixed in master. However your original issue still stands.

[mhegazy]

@joeduffy and @nmalaguti can you give typescript@next a try tomorrow and let us know if the issue has been resolved.

[joeduffy]

Thanks all, that was fast! I'll give it a try in the AM.

[nmalaguti]

This has resolved the issue with default named classes that I was seeing on 1.7 when using ts@next.

How does this interact with libraries compiled to commonjs using babel?