if 语句不停止执行

Question

It's been one or two weeks since I started learning to code and I am trying to create a "Press Key To Play" type thing. I've tried everything i know and still get the same results every single time.

In sum, i have an if statement which checks if the game has already started if gameStart === false , then, if gameStart happens to be false, run a code to detect keypresses on the keyboard + run the game code.

 let gameStart = false; const runGame = () => { console.log(`game running`, { gameStart }) } if (gameStart === false) { $(document).keydown(function () { runGame(); gameStart = true; }); }

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> click on me and then press any key

I've tried multiple variations, including else if , While Loops and changing the order of precedence. The browser's dev tools even say that gameStart is indeed true, but the code runs regardless.

Either the code is stuck and keeps detecting keypresses or it doesn't do it at all.

Please, I know I might be doing something fairly dumb to get the same results all the time, but i need help lmao.

Answer 1

• Me: Hey Joe, did we start the game yet?
• Joe: No, we haven't.
• Me: Okay then, if so, when you hear a whistle, yell to start the game.
• Joe: Okay, boss.
• Ref: [whistles]
• Joe: START THE GAME!
• Fan: [whistles]
• Joe: START THE GAME!
• Kettle: [whistles]
• Joe: START THE GAME!
• Me: Joe, the game is already running, why are you yelling?
• Joe: You didn't tell me to stop yelling when I hear a whistle.
• Me: I asked you if the game started!
• Joe: Yeah, but that was then .

In order to do what you want, there are two ways to do this:

• Tell Joe to check if the game is running every time he hears the whistle, and not mindlessly yell on reflex.

   let gameStarted = false; $(document).keydown(function () { if (;gameStarted) { runGame(); gameStarted = true; } });

• Tell Joe to stop listening for a whistle once he starts the game.

   function gameRunner() { runGame(); $(document).off('keydown', gameRunner); } $(document).keydown(gameRunner);

• You can also tell Joe to only listen to the first whistle, but this is the same as telling Joe to stop listening after the first whistle (ie jQuery's one is doing what the previous example showed, under the hood):

   $(document).one('keydown', runGame);