JS 屏蔽按键效果与改变按键效果的示例代码

function document.onkeydown(){                //网页内按下回车触发
  if(event.keyCode==13)
  {
   document.getElementById("loginbtn").click();   
   return false;                               
  }
 }

 

document.onkeydown=MM_KeyPress;

function  MM_KeyPress(num){
    //防止系统退格键
 var keycode = event.keyCode;
 if(keycode ==8)//屏蔽退格健
 {

  event.keyCode = 0;
  //event.returnValue=false;
  return;
 }
 if(keycode >=112 && keycode <=123)//屏蔽f1-12功能键
 {

  event.keyCode = 0 ;
  event.returnValue=false;
  return;
 }
}