Typescript: Optional chaining and assigning to array items

[mehlian]

TypeScript Version: 3.7.2

Search Terms: optional chaining array items

Code
Is there any reason why I cannot do this:

interface MyInterface {
    temp: number;
}

const a: Array<MyInterface | null> = [];

a[0]?.temp = 0;

and instead I'm forced to use something like this?:

interface MyInterface {
    temp: number;
}

const a: Array<MyInterface | null> = [];

if (a[0])
    a[0].temp = 0;

Expected behavior:
a[0] doesn't exists, so assigning number 0 will be skipped.

Actual behavior:
Error: The left-hand side of an assignment expression may not be an optional property access.(2779)

Playground Link: https://www.typescriptlang.org/play/?target=2&ssl=5&ssc=35&pln=5&pc=40#code/JYOwLgpgTgZghgYwgAgLIE8CS5ryQbwChkTlIBbABwC5kQBXcgI2gG5CBfQwhAexADOYZHFoBBKFDjoAPBmyRYiFAB869ADYaAfMgC8yANoBddoTiGADMYD8AOgqV9yS2eAxkACgvWAlMVIfYwcIKmdXIA

Related Issues:

[j-oliveras]

This is not supported by the specification. See https://github.com/tc39/proposal-optional-chaining#not-supported

[DanielRosenwasser]

This is technically not the appropriate venue to discuss it (since it's just part of the ECMAScript feature, not TypeScript) - but just curious, what would you want to happen?

Do you want to create a property? Or do you want to not perform the assignment if it's not there?

[mehlian]

I expected that assignment will be skipped and no property will be created (no side effects).

[typescript-bot]

This issue has been marked 'Working as Intended' and has seen no recent activity. It has been automatically closed for house-keeping purposes.