Object spread incorrectly compiles getter

TypeScript Version: 2.9.1

Search Terms:
object spread getter

Code

const A = { a: 1 };
const X = { ...A, get x() { return this.a } };
const Y = { a: A.a, get x() { return this.a } };
console.log(X.x, Y.x)

Expected behavior:
1 1

Actual behavior:
undefined 1

The proposal says that get x() should not be called (section Getters on the Object Initializer).

Executing the code in Chrome (66) console produces the expected behavior.

Playground Link:
link

Same issue happens with Babel. The solution would be to use Object.getOwnPropertyDescriptors() to get properties with their values and/or getters/setters, instead of just iterating over properties.

I just came across this one. Here's another piece of code to demonstrate the issue:

var x = {
  ...{}, 
  get r(){
    return Math.random();
  }
};
console.log(x.r);
console.log(x.r);
console.log(x.r);

In JS that logs 3 different random values. In TS, it logs a single random value thrice.

More at https://stackoverflow.com/questions/60861329/typescript-bug-this-difference-between-get-syntax-and-definepropertys-g .

Just ran into this issue; it still exists in 4.9.4. Babel TypeScript works correctly.

Starting in 6.0 the minimum downlevel target will be ES6, which includes Object.assign, so there's no invocation of the spread helper anymore. Closing as moot.

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Object spread incorrectly compiles getter #24799

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Object spread incorrectly compiles getter #24799

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Buslowicz commented on Sep 21, 2018

SBhojani commented on Mar 26, 2020

guitarino commented on Jan 7, 2023

RyanCavanaugh commented on Jul 23, 2025

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