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`typescript` preset: incompatible with `+=` operator inside arrow functions, nested in ternary

See original GitHub issue

Bug Report

I would like to work on a fix! I have close to zero experience with Babel’s internals though. I would not be offended, if you think you can fix it yourself quicklier.

Current Behavior The typescript preset is incompatible with d3-array/cumsum.js. The issue seems to only occur for arrow functions using the += operator, nested inside a ternary. When typescript is disabled, the code compiled without any issues.

Input Code

Original broken d3-array/cumsum.js: REPL
Minimal reproduction: REPL

0 ? v => (sum += v) : v => 0;

/repl.ts: Only ‘=’ operator can be used for specifying default value. (1:13)

1 | 0 ? v => (sum += v) : v => 0;

Expected behavior/code Babel should compile the above code with typescript enabled.

Issue Analytics

State:
Created 4 years ago
Reactions:25
Comments:40 (17 by maintainers)

Top GitHub Comments

9reactions

IlyaSemenovcommented, Oct 30, 2020

@pelly You need to check your yarn.lock and manually merge the duplicate elements that you’ve probably got after yarn add d3-array@2.3.3:

-"d3-array@1.2.0 - 2":
-  version "2.5.1"
-  resolved "https://registry.yarnpkg.com/d3-array/-/d3-array-2.5.1.tgz#cc785e1c4b560a34b8c77af9e6709bdf3f2ee117"
-  integrity sha512-cKvAlQZUKhXInw5mosJMtAYsY3dDYwTess/WOFUQTGcr8xV04SZMJs6n6QznsqZC5vJTkvZuCgsH9fo981ysPA==
-
-d3-array@2.3.3:
+d3-array@2.3.3, "d3-array@1.2.0 - 2":
   version "2.3.3"
   resolved "https://registry.yarnpkg.com/d3-array/-/d3-array-2.3.3.tgz#e90c39fbaedccedf59fc30473092f99a0e14efa2"
   integrity sha512-syv3wp0U5aB6toP2zb2OdBkhTy1MWDsCAaYk6OXJZv+G4u7bSWEmYgxLoFyc88RQUhZYGCebW9a9UD1gFi5+MQ==

A safer approach would be to add a static resolution to package.json:

{
  "resolutions": {
    "d3-array": "2.3.3"
  }
}

and re-run yarn.

6reactions

mstsskcommented, Dec 17, 2020

I had same problem. I’m wondering if ignoring cumsum.js could be a workaround.

// babel.config.js
module.exports = function () {
  return {
    ignore: [new RegExp("d3-array/src/cumsum.js")],
    // other configs...
  }
};

Notes:

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