Disable the refresh key F5 on the keyboard.

<Script language = "JavaScript"> <! -- // Shield right-click, CTRL + N, Shift + F10, F11, F5 refresh, backspace key // Author: meizz (plum blossom rain) 2002-6-18 function document. oncontextmenu () {event. returnvalue = false;} // right-click the screen and select function window. onhelp () {return false} // block the F1 help function document. onkeydown () {If (window. event. altkey) & (window. event. keycode = 37) | // mask Alt + direction key trim (window. event. keycode = 39) // block Alt + direction keys → {alert ("You are not allowed to use Alt + direction keys to move forward or backward the webpage! "); Event. returnvalue = false;}/* Note: this does not really block Alt + direction keys, because when Alt + direction keys pop up the warning box, press and hold the Alt key. Use the mouse to drop the warning box. This blocking method will become invalid */If (event. keycode = 8) | // specifies the event that is used to block the unsigned deletion key. keycode = 116) | // block the F5 refresh key (event. ctrlkey & event. keycode = 82) {// Ctrl + R event. keycode = 0; event. returnvalue = false;} If (event. keycode = 122) {event. keycode = 0; event. returnvalue = false;} // block F11 if (event. ctrlkey & event. keycode = 78) event. returnvalue = false; // block Ctrl + n if (event. shiftkey & event. keycode = 121) event. returnvalue = false; // block SHIFT + F10 if (window. event. srcelement. tagname = "A" & window. event. shiftkey) window. event. returnvalue = false; // block shift with the left mouse button to open a new page if (window. event. altkey) & (window. event. keycode = 115) // mask Alt + F4 {window. showmodelessdialog ("about: blank", "", "dialogwidth: 1px; dialogheight: 1px"); Return false ;}</SCRIPT>