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a?.b.c() produces different result than a?.b!.c()

See original GitHub issue

Bug Report

I would like to work on a fix!

Input Code

REPL or Repo link if applicable:

a?.b.c()
a?.b!.c()

Actual behavior

"use strict";

var _a, _a2;

(_a = a) === null || _a === void 0 ? void 0 : _a.b.c();
((_a2 = a) === null || _a2 === void 0 ? void 0 : _a2.b).c();

Expected behavior/code The ! should have no effect on the produced code.

Problem: Suppose a is null, then the second line can be reduced to:

   ((_a2 = a) === null || _a2 === void 0 ? void 0 : _a2.b).c()
=> ((a2 = null) === null || _a2 === void 0 ? void 0 : _a2.b).c()
=> (null === null || _a2 === void 0 ? void 0 : _a2.b).c()
=> (true ? void 0 : _a2.b).c()
=> undefined.c()

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

Filename: babel.config.js

{
  "presets": ["@babel/preset-typescript", "@babel/preset-stage-3"]
}

Environment

Babel version(s): 7.7.7
How you are using Babel: https://babeljs.io/repl

Possible Solution ¯\_(ツ)_/

Additional context/Screenshots Add any other context about the problem here. If applicable, add screenshots to help explain.

Issue Analytics

State:
Created 4 years ago
Comments:5 (3 by maintainers)

Top GitHub Comments

2reactions

macabeuscommented, Jan 4, 2020

I’m working in a fix to this bug.

0reactions

alex-kinokoncommented, Mar 22, 2020

@nicolo-ribaudo There’s a bug filed at the TypeScript repo.

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