how to prevent/control refresh, navigation or close of a webpage

[DaleHohm]

Under the right circumstances, you may find this very useful...

Note that this can be used on any webpage, whether you (_IE)Create it or (_IE)Attach to it on the Internet.

expandcollapse popup

; Example demonstrating how to prevent/control refresh, navigation or close of a webpage.
; Particularly useful when you are writing an application with extensive Dynamic HTML
; that can be wiped out with a simple page refresh.

#include <IE.au3>

$oIE = _IECreate()

; Add HTML to blank page
$oBody = _IETagnameGetCollection($oIE, "body", 0)
_IEDocInsertHTML($oBody, "<a href=http://www.autoitscript.com>Navigate to http://www.autoitscript.com</a><p>")
_IEDocInsertHTML($oBody, "<BUTTON id=b1 value='Normal Exit'>Normal Exit</button>&nbsp;")
_IEDocInsertHTML($oBody, "<BUTTON id=b2 value='Safe Exit'> Safe Exit </button>")

; Get references to buttons and setup event handlers
$oButton1 = _IEGetObjById($oIE, "b1")
$oButton2 = _IEGetObjById($oIE, "b2")
$oEvtButton1 = ObjEvent($oButton1, "evtButton_")
$oEvtButton2 = ObjEvent($oButton2, "evtButton_")

; Setup random alert string to appear in popup, add a function to be called when onbeforeunload is triggered.
; This is the "magic" in this example
$sRandom = "MY-ALERT-" & Random(1000000, 9999999, 1) 
IEHeadInsertScript($oIE, "function promptBeforeUnload() { return '" & $sRandom & "'; }")
IEEval($oIE, "window.onbeforeunload = promptBeforeUnload;")

; With this Javascript injected in the page, any attempt to navigate, refresh or close will
; result in a popup like the following.  The key is adding text to the Return statement of the
; function that is bound to the onbeforeunload event.
;
; The TrapAlert routine called in the idle loop watches for the unique string in the alert ($sRandom),
; quickly covers the alert with a splash screen and presses Cancel to abort the action.
;
; This is not a foolproof method if someone is trying to break out because there is often
; enough of a lag for the user to press OK, but in the right circumstances is very effective.

; ---------------------------------------------------------------
; Are you sure you want to navigate away from this page?
;
; MY-ALERT-2522442
;
; Press OK to continue, or Cancel to stay on the current page.
;
;                                             OK       Cancel
; ---------------------------------------------------------------

While __IEIsObjType($oIE, "browser")
    TrapAlert()
    Sleep(200)
WEnd

; --------------- Functions ---------------
Func TrapAlert()
    If WinExists("", $sRandom) Then
        ControlClick("", $sRandom, "Button2")
        SplashTextOn("Navigation not allowed!", _
            "Use the controls supplied or you will lose all of your work!", -1, -1, -1, -1, 33)
        Sleep(5000)
        SplashOff()
    EndIf
EndFunc

Func evtButton_onclick()
    Local $o_object = @COM_EventObj
    Switch $o_object.value
        Case "Normal Exit"
            $oIE.quit
        Case "Safe Exit"
            ; Remove the function tied to onbeforeunload and defeat the trap so that 
            ; normal navigation, refresh or close can occur
            IEEval($oIE, "window.onbeforeunload = '';")
            $oIE.quit
    EndSwitch
EndFunc

Func IEEval($o_object, $s_eval)
    Return $o_object.document.parentwindow.eval($s_eval)
EndFunc

Func IEHeadInsertScript($o_object, $s_script)
    Local $o_head, $o_element
    $o_head = _IETagNameGetCollection($o_object, "head", 0)
    $o_element = $o_object.document.createElement('script')
    $o_element.type = 'text/javascript'
    $o_element.text = $s_script
    Return $o_head.appendChild($o_element)
EndFunc

Dale

Edited February 16, 2010 by DaleHohm

[Zedna]

Thanks Dale!

Nice/educative.

[AdmiralAlkex]

Not to be picky but (_IE)Atatch??

[DaleHohm]

Not to be picky but (_IE)Atatch??

Oh, ok, glad you're not being picky.

[AdmiralAlkex]

Oh, ok, glad you're not being picky.

Well maybe you should fix that anyway, otherwize there will eventually come a noob and ask "what is _IEAtatch()?