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Array.prototype[Symbol.unscopables] is not a function #34610
Description
TypeScript Version: 3.7.0-dev.20191018
Search Terms:
- Array
- @@unscopables
Code
const x = [][Symbol.unscopables];
console.log(x.copyWithin);
const y = [][Symbol.unscopables]();
console.log(y.copyWithin);Expected behavior:
x.copyWithin occurs no error, and [][Symbol.unscopables]() occurs type error.
Actual behavior:
x.copyWithin occurs type error, and [][Symbol.unscopables]() occurs runtime exception.
Related Issues:
Activity
NicholasLYang commentedon Oct 22, 2019
Is this because
[Symbol.unscopables]is not a function but marked as one in the lib declaration file? According to MDN,object[Symbol.unscopables]should be an object. I removed the parens on this line and it appeared to fix the problem.Building works correctly with the change but my IDE complains:
TS2717: Subsequent property declarations must have the same type. I'm not really sure where the other property declarations ofSymbol.unscopablesare. Could I get a point in the right direction? Also should I change all the tests that use[Symbol.unscopables]()to[Symbol.unscopables]?ExE-Boss commentedon Jan 31, 2021
Ron Buckton (@rbuckton) This is still broken, so I’m fixing it in #42566.