問(wèn)題描述

如果用戶按住鍵，則會(huì)觸發(fā)多個(gè) keydown 事件.出于可用性原因，我需要使用 keydown，而不是 keyup，但我想避免這種情況.我的相關(guān)代碼如下:

If the user holds down the key, multiple keydown events are fired. For usability reasons I need to use keydown, not keyup, but I want to avoid this situation. My relevant code is the following:

$(document).keydown(function(e) { 
        var key = 0;


        if (e == null) { key = event.keyCode;}  
        else {  key = e.which;} 


        switch(key) {
            case config.keys.left:                
              goLeft();
              break;
            case config.keys.up:                        
              goUp();
              break;
            case config.keys.right:                     
              goRight();
              break;
            case config.keys.down:                
              goDown();
              break;
            case config.keys.action:              
              select();
              break;
        }     
      });

因此，例如，當(dāng)用戶按住向下鍵時(shí)，會(huì)多次觸發(fā) goDown().即使用戶按住鍵，我也希望它只觸發(fā)一次.

So when the user holds down the down key, for example, goDown() is fired multiple times. I would like it to fire just once even if the user holds the key down.

推薦答案

使用 event.repeat 檢測(cè)事件是否重復(fù).然后，您可以在允許處理程序第二次執(zhí)行之前等待keyup".

Use event.repeat to detect whether or not the event is repeating. You could then wait for "keyup" before allowing the handler to execute a second time.

var allowed = true;

$(document).keydown(function(event) { 
  if (event.repeat != undefined) {
    allowed = !event.repeat;
  }
  if (!allowed) return;
  allowed = false;
  //...
});

$(document).keyup(function(e) { 
  allowed = true;
});
$(document).focus(function(e) { 
  allowed = true;
});

這篇關(guān)于如何避免 JavaScript 中自動(dòng)重復(fù)的 keydown 事件?的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！