What happens when passing a triangle to the shape union area function?

Added: 2026-05-16

[00:00:00]Here's a TypeScript developer challenge for an issue that often slips into real code bases. You handle all your cases until, of course, someone adds one [music] more.

[00:00:11]Take a look at this shape union and area function. Now, someone calls it with a triangle.

[00:00:17]What happens?

[00:00:18]>> [music] >> Is it A, compile error? B, returns 25?

[00:00:23]Or C, returns undefined?

[00:00:26]Drop your answer in the comments below.