onkeypress 和 onkeydown 是有區別，下面將講解 onkeypress 與 onkeydown 事件的區別。
onkeypress 事件在用戶按下并放開任何字母數字鍵時發生。但是系統按鈕（例如：箭頭鍵、功能鍵）無法得到識別。
onkeydown 事件在用戶按下任何鍵盤鍵（包括系統按鈕）時發生。
具體區別：
1. 一個放開一個沒有放開，onkeydown 先于 onkeypress 發生。
2.onkeypress 無法系統按鈕。
2.onkeydown 捕獲的 keyCode 不區分字母大小，而 onkeypress 區分。

onkeypress是在用戶按下并放開任何字母數字鍵時發生。系統按鈕（例如，箭頭鍵和功能鍵）無法得到識別。
onkeyup 是在用戶放開任何先前按下的鍵盤鍵時發生。
onkeydown 是在用戶按下任何鍵盤鍵（包括系統按鈕，如箭頭鍵和功能鍵）時發生。

onkeypress
As of Microsoft® Internet Explorer 4.0, the onkeypress event fires and can be canceled for the following keys:

Letters: A - Z (uppercase and lowercase)
Numerals: 0 - 9
Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? / | ' ` " ~
System: ESC, SPACEBAR, ENTER

onkeydown
As of Microsoft® Internet Explorer 4.0, the onkeydown event fires for the following keys:

Editing: DELETE, INSERT
Function: F1 - F12
Letters: A - Z (uppercase and lowercase)
Navigation: HOME, END, LEFT ARROW, RIGHT ARROW, UP ARROW, DOWN ARROW
Numerals: 0 - 9
Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? / | ' ` " ~
System: ESC, SPACEBAR, SHIFT, TAB

As of Internet Explorer 5, the event also fires for the following keys:

Editing: BACKSPACE
Navigation: PAGE UP, PAGE DOWN
System: SHIFT+TAB

As of Internet Explorer 5, this event can be canceled for the following keys and key combinations by specifying event.returnValue=false:

Editing: BACKSPACE, DELETE
Letters: A - Z (uppercase and lowercase)
Navigation: PAGE UP, PAGE DOWN, END, HOME, LEFT ARROW, RIGHT ARROW, UP ARROW, DOWN ARROW
Numerals: 0 - 9
Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? / | ' ` " ~
System: SPACEBAR, ESC, TAB, SHIFT+TAB

You can cancel all keys that fire the onkeydown event in HTML Applications, including most accelerator keys, such as ALT+F4.

In Internet Explorer 4.0, you cannot cancel the onkeydown event, but you can use the onkeypress event to cancel keyboard events.

兩個一起按，可以這樣：
代碼如下:
if( window.event.shiftKey && event.keyCode==xx)

function document_onpress()
{

if(event.keyCode=='13')
{
document.all.div_Line.style.pixelLeft=document.all.div_Line.style.pixelLeft+1;
document.all.div_Q.style.pixelLeft=document.all.div_Q.style.pixelLeft+1;
document.all.div_T.style.pixelLeft=document.all.div_T.style.pixelLeft+1;

}