onkeypress 和 onkeydown 是有區別，下面將講解 onkeypress 與 onkeydown 事件的區別。 
onkeypress 事件在使用者按下並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 事件在使用者按下任何鍵盤鍵（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 先於 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是在使用者按下並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 是在使用者放開任何先前按下的鍵盤鍵時發生。 
onkeydown 是在使用者按下任何鍵盤鍵（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： 

複製程式碼

程式碼如下:

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; 

}