Javascript屏蔽键盘的代码

请写一段Javascript的代码防止用户提交表单后刷新网页（例如按F或按IE上的刷新按钮）重新提交表单内容页面提交是在本页面提交到本页面大家帮帮忙？

下面的代码只是实现了屏蔽鼠标右键Ctrl+nshift+FF刷新退格键

function KeyDown(){

//屏蔽鼠标右键Ctrl+nshift+FF刷新退格键

//alert(ASCII代码是+eventkeyCode);

if ((windoweventaltKey)&&

((windoweventkeyCode==)|| //屏蔽 Alt+ 方向键 ←

(windoweventkeyCode==))){ //屏蔽 Alt+ 方向键 →

alert(不准你使用ALT+方向键前进或后退网页！);

eventreturnValue=false;

}

if ((eventkeyCode==) || //屏蔽退格删除键

(eventkeyCode==)|| //屏蔽 F 刷新键

(eventkeyCode==)|| //屏蔽 F 刷新键

(eventctrlKey && eventkeyCode==)){ //Ctrl + R

eventkeyCode=;

eventreturnValue=false;

}

if ((eventctrlKey)&&(eventkeyCode==)) //屏蔽 Ctrl+n

eventreturnValue=false;

if ((eventshiftKey)&&(eventkeyCode==)) //屏蔽 shift+F

eventreturnValue=false;

if (windoweventsrcElementtagName == A && windoweventshiftKey)

windoweventreturnValue = false; //屏蔽 shift 加鼠标左键新开一网页

if ((windoweventaltKey)&&(windoweventkeyCode==)){ //屏蔽Alt+F

windowshowModelessDialog(about:blankdialogWidth:px;dialogheight:px);

return false;}

}