I have moved your post to it’s own topic. How would you like to mix text and numbers? Adding a letter and a number isn’t always well defined.
I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
The addition operator ( + ) produces the sum of numeric operands or string concatenation, so if you are passing a string will treat all as strings and concatenate them
add(1, "2") // "12" trated as string and concatenated
If you want to always treat them as numbers you need to be explicit about it
Hope it helps.