Array.at() doesn't consider array length #63130
Description
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I'm using deno, so here is its version and the TypeScript version it's using:
$ deno --version
deno 2.6.9 (stable, release, x86_64-pc-windows-msvc)
v8 14.5.201.2-rusty
typescript 5.9.2
This expression results in an error, but should not:
const lParts: string[] = [];
if (lParts.length > 0) && lParts.at(-1).endsWith('\n') ...because obviously if an array has at least one item in it, there's an item in the next to last position and because of the way lParts is defined, the array cannot have any undefined items in it.
There is a workaround, though it shouldn't be needed, which is:
const lParts: string[] = [];
if (lParts.length > 0) && lParts.at(-1)?.endsWith('\n') ...which avoids calling endsWith() if lParts.at(-1) were to return undefined (which it cannot)
🕗 Version & Regression Information
- This changed between versions ______ and _______
- This changed in commit or PR _______
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
- I was unable to test this on prior versions because _______
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💻 Code
// Your code here🙁 Actual behavior
It fails with an error
🙂 Expected behavior
It shouldn't give an error
Additional information about the issue
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