[ajusa]

Oh wow, I never noticed that myself. I'll fix it once I'm at my computer, thanks for pointing it out! The fix will probably be something like

    if letter not in (.bg-warning in first .guess).innerText then add .bg-warning

Haven't tested as I'm on my phone, but seems like a simple enough fix.

[anonymoushn]

I don't think it's that simple. For HOUSE, guessing BEERS should get you WYWYW

[Aethylia]

I have been trying to figure this out myself. The algorithm I'm using is to colour yellow only if the count of that letter before that occurance in the guess, is less than the count of that letter in the target word.

[joeframbach]

Looks good, here are some test cases off the top of my head.

guess: "SASSY", target: "BRASS", expect either "YYBGB" or "BYYGB". I believe your algorithm would return "YYYGB".

guess: "BRASS", target: "SASSY", expect "BBYGY"

guess: "ASSET", target: "BRASS", expect "YYYBB"

guess: "BRASS", target: "ASSET", expect "BBYYY"