鼠標和鍵盤單獨使用都沒問題。但是先用鼠標點擊開始，再敲enter鍵，這時候沒有辦法停止。不知道我的代碼哪里有錯。

var?arr?=?['R','R','R','R','R','R','R','R','R','R','SR','SR','SR','SR','SR','SSR'];
var?title?=?document.getElementById('title'),
????timer?=?null,
????flag?=?0;

window.onload?=?function(){
????var?start?=?document.getElementById('start'),
????????stop?=?document.getElementById('stop');
????//開始抽獎
????start.onclick?=?startFunc;
????//停止抽獎
????stop.onclick?=?stopFunc;
????//鍵盤事件
????document.onkeyup?=?keyupFunc;
}
function?startFunc(){
????var?title?=?document.getElementById('title'),
????????start?=?document.getElementById('start');
????clearInterval(timer);
????timer?=?setInterval(function(){
????????var?random?=?Math.floor(Math.random()*arr.length);
????????title.innerHTML?=?arr[random];
????},50)
????start.disabled?=?true;
????start.style.backgroundColor?=?'#ccc';
????flag?=?1;
}
function?stopFunc(){
????clearInterval(timer);
????start.disabled?=?false;
????start.style.backgroundColor?=?'#1aa';
????flag?=?0;
}
function?keyupFunc(event){
????event?=?event?||?window.event;
????if(event.keyCode?!==?13){
????????return?null;
????}else{
????????flag?==?0???startFunc()?:?stopFunc();
????}
}