Helpers missing from output file for a TS script (instead of module)

[mohd-akram]

I get a Uncaught ReferenceError: __awaiter is not defined when compiling a file with async. I'm using the latest TypeScript (2.6.2), rollup (0.53.0) and plugin (0.9.0).

main.ts

async function main() {
}
main();

rollup.config.js

import typescript from 'rollup-plugin-typescript2';

export default {
  output: {
    format: 'iife'
  },
  plugins: [
    typescript()
  ]
}

tsconfig.json

{
  "compilerOptions": {
    "lib": [
      "es2015"
    ]
  }
}

main.js:

(function () {
'use strict';

function main() {
    return __awaiter(this, void 0, void 0, function () {
        return __generator(this, function (_a) {
            return [2 /*return*/];
        });
    });
}
main();

}());

[ezolenko]

Looks like you are hitting this one: microsoft/TypeScript#12167 -- TS treats this as global script, not a module, so it doesn't generate tslib imports.

When I add any import or export to main.ts, I get __awaiter/__generator imported.

The plugin forces "noEmitHelpers": true, "importHelpers": true to avoid multiple copies of tslib. Let me know if you can't make your code into a module for some reason, so far I haven't seen a reason those options should not be forced.

[mohd-akram]

Did a quick test — seems like setting importHelpers: true alone is sufficient to prevent duplicates while fixing this problem.

[ezolenko]

If TS emits helpers in each js file (like it would do when "noEmitHelpers": false), then rollup will happily rename them when making a bundle, so you'd end up with __generator$1, __generator$2, etc.

Could you post the test? Did you use 2 separate modules? Last time I checked it did that anyway, I'll try again later.

[mohd-akram]

I modified rollup-plugin-typescript2.cjs.js in node_modules to remove noEmitHelpers: true and didn't find any duplicates of __awaiter. I then removed importHelpers: true which caused __awaiter$1 to be added to the output. Both modules had async functions in them.

To test with tsc:

tsc main.ts --importHelpers --module es2015 --lib es2015 --moduleResolution node

main.ts:

import f from './module';

async function main() {
  await f();
}
main();

module.ts:

async function f() {
}
export default f;

main.js:

import * as tslib_1 from "tslib";
import f from './module';
function main() {
    return tslib_1.__awaiter(this, void 0, void 0, function () {
        return tslib_1.__generator(this, function (_a) {
            switch (_a.label) {
                case 0: return [4 /*yield*/, f()];
                case 1:
                    _a.sent();
                    return [2 /*return*/];
            }
        });
    });
}
main();

module.js

import * as tslib_1 from "tslib";
function f() {
    return tslib_1.__awaiter(this, void 0, void 0, function () {
        return tslib_1.__generator(this, function (_a) {
            return [2 /*return*/];
        });
    });
}
export default f;

[ezolenko]

Thanks, I'll test on a few versions of typescript and remove noEmitHelpers override if it works everywhere.

[ezolenko]

This is in 0.10.0