如何设置快捷键

用javascript 如何设置组合快捷触发一个函数?
如按Ctrl+Enter 触发window.close();
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1<script>   
2function document.onkeydown(){   
3if(event.keyCode==13&&event.ctrlKey)window.close()   
4}   
5</script>

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 1<body onkeydown="aa()">
 2<input name="aaa" onkeydown="alert(event.keyCode)" type="text"/>
 3<script language="JavaScript">   
 4<!--   
 5function aa(){   
 6if((event.ctrlKey) && (event.keyCode==13)){   
 7window.close();   
 8}   
 9}   
10//-->   
11</script>   
12\---------------------------------------------------------------   
13  
14function document.onkeydown()   
15{   
16if ((window.event.ctrlKey)&amp;&amp;(window.event.keyCode==13)){   
17window.close()   
18return false;}   
19}</body>