jQuery键盘事件处理器按住 [英] jQuery keyboard event handler press and hold

问题描述

我想为游戏创建一个简单的事件处理程序，这里是我的代码

i want to create a simple event handler for a game, here's my code

     $(document).keydown(function(e){
      switch(e.keyCode){
        case 65: //left (a)

          console.log('left');
          break;

        case 68: //right (d)

          console.log('right');
          break;

      }
    });

问题是如果我按住一个键，稍后会触发多次。
我该如何防止这种行为？我在Google Chrome上运行我的代码

the problem is that if i press and hold a key, after a little it triggers multiple times. how can i prevent this behaviour? i'm running my code on google chrome

推荐答案

这是重点。您可以通过记住您已经知道钥匙已经关闭，您可以击败它：

This is key repeat. You can defeat it if you want to, by remembering that you already know the key is down:

// A map to remember in
var keysdown = {};

// keydown handler
$(document).keydown(function(e){

  // Do we already know it's down?
  if (keysdown[e.keyCode]) {
      // Ignore it
      return;
  }

  // Remember it's down
  keysdown[e.keyCode] = true;

  // Do our thing
  switch(e.keyCode){
    case 65: //left (a)

      console.log('left');
      break;

    case 68: //right (d)

      console.log('right');
      break;

  }
});

// keyup handler
$(document).keyup(function(e){
  // Remove this key from the map
  delete keysdown[e.keyCode];
});

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旁注：我想当你使用jQuery， e.which 是更可靠的属性，如它通过jQuery进行标准化。

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Side note: I think when you're using jQuery, e.which is the more reliable property, as it's normalized for you by jQuery.

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