"1" + 2 === "12" is not unique to JS (sans the requirement for the third equals sign), it’s a common feature of multiple strongly typed languages. imho it’s fine.

EDIT: I did some testing:

What it works in:

• JS
• TS
• Java
• C#
• C++
• Kotlin
• Groovy
• Scala
• PowerShell

What produces a number, instead of a string:

• PHP
• SQL
• Perl
• VB
• Lua

What it doesn’t work in:

• R
• C
• Go
• Swift
• Rust
• Python
• Pascal
• Ruby
• Objective C
• Julia
• Fortran
• Ada
• Dart
• D
• Elixir

And MATLAB appears to produce 51, wtf idk

The sort of comeback so good you think of it later on and write a comic, wishing you’d said it at the time