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I read here that I don't need to put a semicolon after default exports. So this program has an unnecessary semicolon:

export default function() {};

But if my module continues like this:

export default function() {};

(() => {
  // creating a new function scope
})();

then I can't leave the semicolon.

So what is going on here? The grammar says I don't need the semicolon but if I leave it the code means something else?

UPDATE:

If I leave the semicolon:

export default function() {}

(() => {
  // creating a new function scope
})();

then the exported function gets called instead of being exported. babeljs.io piles the latter into:

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});

exports["default"] = (function () {})(function () {
  // creating a new function scope
})();

;
module.exports = exports["default"];

More precisely after it gets called an error is thrown, because the return value of the first function also gets called (but that is not a function). The error I get in chrome is this:

Uncaught TypeError: (intermediate value)(...) is not a function(…)

I read here that I don't need to put a semicolon after default exports. So this program has an unnecessary semicolon:

export default function() {};

But if my module continues like this:

export default function() {};

(() => {
  // creating a new function scope
})();

then I can't leave the semicolon.

So what is going on here? The grammar says I don't need the semicolon but if I leave it the code means something else?

UPDATE:

If I leave the semicolon:

export default function() {}

(() => {
  // creating a new function scope
})();

then the exported function gets called instead of being exported. babeljs.io piles the latter into:

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});

exports["default"] = (function () {})(function () {
  // creating a new function scope
})();

;
module.exports = exports["default"];

More precisely after it gets called an error is thrown, because the return value of the first function also gets called (but that is not a function). The error I get in chrome is this:

Uncaught TypeError: (intermediate value)(...) is not a function(…)

• javascript
• ecmascript-6
• babeljs

Share Improve this question Follow edited May 23, 2017 at 11:44 CommunityBot 111 silver badge asked Dec 5, 2015 at 22:29 Tamas HegedusTamas Hegedus 30k1212 gold badges6666 silver badges101101 bronze badges 4

• What makes you not able to leave the semicolon in the second case? Does something give you an error? – loganfsmyth Commented Dec 5, 2015 at 22:39
• @loganfsmyth please see my update – Tamas Hegedus Commented Dec 5, 2015 at 22:49
• possible duplicate of Default export in ES6. Why don't you need a semicolon? (if your question wasn't about the babel bug) – Bergi Commented Dec 6, 2015 at 13:21
• 1 @Bergi I read here that I don't need to put a semicolon... I forgot to link the question :( the question you linked inspired my own. At first I suspected inconsistency in the spec itself, then it turned out it is probably a babel bug. – Tamas Hegedus Commented Dec 6, 2015 at 13:56

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1 Answer 1

Sorted by: Reset to default 13

You don't need to add a semicolon after a export default when it's followed by a function declaration, that's what the grammar says.

Babel is wrong, I've filed a bug against it. That code should be interpreted as exporting the function and then running the IIFE as an IIFE.

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