屏蔽F1~F12的快捷键的js函数

function window.onhelp(){return false} //屏蔽F1帮助 

/*keyCod从113-123分别禁用了F2-F12键,13禁用了回车键(Enter),8禁用了退格键(BackSpace)*/ 

 

document.onkeydown = function(){ 

if(window.event && window.event.keyCode == 113) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 114) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 115) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 116) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 117) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 118) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 119) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 120) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 121) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 122) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 123) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 13) { 

window.event.keyCode = 505; 

} 

if(window.event && window.event.keyCode == 8) { 

alert(str+"\n请使用Del键进行字符的删除操作！"); 

window.event.returnValue=false; 

} 

if(window.event && window.event.keyCode == 505){ 

　　alert(str) 

window.event.returnValue=false; 

} 

}