屏蔽只读文本框退回按键返回上一页

只要放在JS中即可生效

//这段代码用来只读文本框退回按键返回上一页
      document.onkeydown = check;
      function check(e) {
          var code;
          if (!e) var e = window.event;
          if (e.keyCode) code = e.keyCode;
          else if (e.which) code = e.which;
          if (((event.keyCode == 8) &&                                                    //BackSpace
                  ((event.srcElement.type != "text" &&
                      event.srcElement.type != "textarea" &&
                      event.srcElement.type != "password") ||
                      event.srcElement.readOnly == true)) ||
              ((event.ctrlKey) && ((event.keyCode == 78) || (event.keyCode == 82)) ) ||    //CtrlN,CtrlR
              (event.keyCode == 116) ) {                                                   //F5
              event.keyCode = 0;
              event.returnValue = false;
          }
          return true;
      }