按键同时按下 [英] Keys pressed at the same time

问题描述

我可以在Javascript中知道同时按下的键数吗？

Can I know the number of keys pressed at the same time in Javascript?

如果是这样，我怎么能得到一个的数组？ keyCode ？

If so, how can I have an array of their keyCode?

推荐答案

您可以收听keydown和keyup事件。

You can listen for keydown and keyup events.

var keys = { length: 0 };

document.onkeydown = function(e){
    if(!keys[e.keyCode])   {
        keys[e.keyCode] = true;
        keys.length++;
    }
}

document.onkeyup = function(e){
    if(keys[e.keyCode])   {
        keys[e.keyCode] = false;
        keys.length--;
    }
}

然后所有 true 是当前按下的那些。

Then all the keys that are true are the ones that are pressed currently.

小提示演示感谢@Esailija： http://jsfiddle.net/maniator/Gc54D/

Fiddle demo thanks to @Esailija: http://jsfiddle.net/maniator/Gc54D/

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