In this game, you have 10 chances to guess a four-digit number. It has to be four differnt digits, so the answer won't be like 6666, or 1212. Please note the first digit could be 0.
You will see how good was your guess in the right panel. "xA" means among the four digits you guessed, x of them are correct for BOTH number and position. "yB" means y of the digits are ONLY correct for number.
For example, if the answer is 0239 and your guess is 1309, the result would be "1A2B" since you correctly guessed "9" to be fourth digit (1A) and you are also right that "0" and "3" are in the answer but not at your guessed position (2B). If you could get a "4A0B" in 10 tries, you win the game!
After a few guesses, you will become more and more sure what digits are in the answer. Based on your guess history, with luck and your high IQ, you will beat the game.
If you feel this is too difficult, don't forget you have and only have 1 hint. Use it wisely
It can be a real chanllege. Are you up to it?
Extra
Hint: DevTools console knows better.^_^