Javascript reference error but works when I use a bookmarklet - javascript

I'm trying to execute some Javascript on a page that's already fully loaded.
To test the javascript, I created a bookmarklet, clicked it while the page was loaded, and it executed properly:
javascript:(array.find('value').__showAllRecords(event))
I wanted to use this Javascript in an AppleScript I'm writing that sends it to chrome, but for some reason, I'm getting this error:
Uncaught ReferenceError: array is not defined
at <anonymous>:1:1
It only happens when I run my script in my AppleScript editor, not when I use the bookmarklet. Here's my AppleScript code:
tell application "Google Chrome"
execute front window's active tab javascript "array.find('value').__showAllRecords(event)"
end tell

The variable array is created at some point in time after your script executes, since you don't know when you could retry until it does exist:
(function(){
function trySomething(){
try{
array.find('value').__showAllRecords(event);
console.log("worked, stop trying");
clearInterval(timer);
}catch(e){
console.log("didn't work, try again",e);
}
}
var timer = setInterval(trySomething,1000);
}())
//create the array object some time in the future (not actually an Array type)
//this is not part of your script but would be created by the page
//at some point
setTimeout(
()=>window.array={find:x=>({__showAllRecords:x=>x})}
,6000
)

Unfortunately, applescript does not have access to the non default globals. See the thread https://bugs.chromium.org/p/chromium/issues/detail?id=543437
But there is a workaround, what you can do is set the array as innerHTML of a div and retrieve the value from applescript. So for e.g. this is my div <div id="test">[1,2,3]</div>, you can execute
tell application "Google Chrome"
execute front window's active tab javascript "console.log(document.getElementById(\"test\").innerHTML)"
end tell
Hope this helps

Related

Unable to get property 'style' of undefined or null reference but works in another server

I have a classic asp project. In one of my pages i have to call a javascript function. That call does not have any problem and works fine on my test server (not localhost, just a server to test he project). But when i deploy it to the actual server, that function does not work. I call this function in onload event.
That function has this type of lines (i cannot write the whole code, because of the company that i work for, does not allow it)
document.getElementById("R6C2_1").style.display = 'block'
document.getElementById("R6C2_2").style.display = 'none'
....
When I try to debug it on IE10, i got "Unable to get property 'style' of undefined or null reference" error. After that, the elements in javascript function are not load. They are not seen on the page.
My main problem is, as i mentioned before differences between servers. I do not understand why it works on one server, but not on another server.
While it's not possible to determine the issue from this information alone, you should look into:
Whether the elements you're looking for actually exist when the code is invoked (use browser debug / breakpoints to look at the page the moment the code is invoked).
If they exist, check if they have the ID you expect (e.g R6C2_1) - if not, why? who creates these IDs? could be a server configuration issue.
Do a debug using the app from each server, and look at the page / DOM, see if there are differences or check if the code is invoked at different times.
These could lead you to pinpoint the issue. Good luck!
In case the elements just take time to be created, you can just wait until they are present:
function ExecuteWhenExists() {
var R6C2_1 = document.getElementById("R6C2_1");
var R6C2_2 = document.getElementById("R6C2_2");
if (R6C2_1 && R6C2_2) {
R6C2_1.style.display = 'block';
R6C2_2.style.display = 'none';
} else {
window.setTimeout(ExecuteWhenExists, 100);
}
}
ExecuteWhenExists();
This will not crash when the elements do not exist, and will just keep trying to execute in a non-blocking way (polling every 0.1 seconds) until they exist.

nsIDOMWindowUtils.isInModalState() not working

I get the utils of the window like this:
var utils = Services.wm.getMostRecentWindow('navigator:browser').
QueryInterface(Components.interfaces.nsIInterfaceRequestor).
getInterface(Components.interfaces.nsIDOMWindowUtils);
then running this code says its not a function:
Services.prompt.alert(null, 'is modal?', utils.isInModalState())
//Exception: utils.isInModalState is not a function
even though it says in the documentation it is.
I am not able to run this code either:
utils.enterModalState()
It runs without error but the window does not enter or leave modal state.
The .isInModalState property is actually tagged [noscript], so it is not available in Javascript, only C++.
.enterModalState() doesn't do what you think it does. It does not make a window UI-modal (like an alert dialog). It just essentially suspends scripts and event processing in the window.

Run greasemonkey script after javascript

I'm trying to modify a variable - which is created in javascript - and run a function to change some visual stuff on a page. But my greasemonkey script is - i guess - running before the javascript, i'm getting an error says function is not defined.
How can I force to run my script after the javascript runs?
Actually what I'm trying to do is very simple. There is a variable called cursort, what I want to do is change that to "data-price" and sort the list again using updateSort(). Here is the code:
var cursort = "data-price";
updateSort();
I had to do something similar, there was a object defined at the end of the page that I wanted to just cancel out, so it's functions wouldn't run (it captured link clicks and ran some stuff).
In the page it was defined like this:
var someObj = { ... }
I made a greasemonkey script (after much trial/error) that looked like this.
window.addEventListener ("load", runAfter, false);
function runAfter() {
unsafeWindow.someObj = null;
}
Now clicking on the links does not trigger all the other actions that were in someObj.
Maybe you can do something like that?

Why does this simple login script work in Tampermonkey but not Greasemonkey?

I have this tiny little script that I run inside Chrome using Tampermonkey and works great.
However, when I use it in Firefox with Greasemonkey, it shows up on the active list, meaning its matching the page but it doesn't actually execute the code. I know it has to be a simple something I am overlooking but its not hitting me.
var myVar=setInterval(function(){myTimer();},100);
function myStopFunction()
{
clearInterval(myVar);
}
function myTimer()
{
var p1 = "Login";
var p2 = "mode=login";
var x = document.body.innerHTML;
if (x.match(p1) && x.match(p2)){
document.documentURI = "/ucp.php?mode=login";
}
myStopFunction();
}
Script Logic/Function
I am using a timer to prevent the script from triggering over and over in a permanent loop.
It simply detects if I am logged into a phpBB forum or not, if not send me to the login page so I can log in.
I am using document URI so that the location of the original is preserved so upon login, it takes me right back to it.
Often phpBB when you log in, it will take you back to the index page so this preserves my original intent of going to the actual link.
This script works perfectly and as expected on Chrome using TM but on Firefox using GM it doesn't trigger, am I missing something here?
From the Firefox spec:
(document.documentURI)
Returns the document location as string. It is read-only per DOM4 specification.
And, indeed, the latest spec still specifies that this attribute must be read only.
If Chrome lets you write this property, then that is non-standard behavior and maybe a bug.
Use location.assign(), or location.replace(), or just programmatically click the login button -- which often preserves the target page.

What causes the error "Can't execute code from a freed script"

I thought I'd found the solution a while ago (see my blog):
If you ever get the JavaScript (or should that be JScript) error "Can't execute code from a freed script" - try moving any meta tags in the head so that they're before your script tags.
...but based on one of the most recent blog comments, the fix I suggested may not work for everyone. I thought this would be a good one to open up to the StackOverflow community....
What causes the error "Can't execute code from a freed script" and what are the solutions/workarounds?
You get this error when you call a function that was created in a window or frame that no longer exists.
If you don't know in advance if the window still exists, you can do a try/catch to detect it:
try
{
f();
}
catch(e)
{
if (e.number == -2146823277)
// f is no longer available
...
}
The error is caused when the 'parent' window of script is disposed (ie: closed) but a reference to the script which is still held (such as in another window) is invoked. Even though the 'object' is still alive, the context in which it wants to execute is not.
It's somewhat dirty, but it works for my Windows Sidebar Gadget:
Here is the general idea:
The 'main' window sets up a function which will eval'uate some code, yup, it's that ugly.
Then a 'child' can call this "builder function" (which is /bound to the scope of the main window/) and get back a function which is also bound to the 'main' window. An obvious disadvantage is, of course, that the function being 'rebound' can't closure over the scope it is seemingly defined in... anyway, enough of the gibbering:
This is partially pseudo-code, but I use a variant of it on a Windows Sidebar Gadget (I keep saying this because Sidebar Gadgets run in "unrestricted zone 0", which may -- or may not -- change the scenario greatly.)
// This has to be setup from the main window, not a child/etc!
mainWindow.functionBuilder = function (func, args) {
// trim the name, if any
var funcStr = ("" + func).replace(/^function\s+[^\s(]+\s*\(/, "function (")
try {
var rebuilt
eval("rebuilt = (" + funcStr + ")")
return rebuilt(args)
} catch (e) {
alert("oops! " + e.message)
}
}
// then in the child, as an example
// as stated above, even though function (args) looks like it's
// a closure in the child scope, IT IS NOT. There you go :)
var x = {blerg: 2}
functionInMainWindowContenxt = mainWindow.functionBuilder(function (args) {
// in here args is in the bound scope -- have at the child objects! :-/
function fn (blah) {
return blah * args.blerg
}
return fn
}, x)
x.blerg = 7
functionInMainWindowContext(6) // -> 42 if I did my math right
As a variant, the main window should be able to pass the functionBuilder function to the child window -- as long as the functionBuilder function is defined in the main window context!
I feel like I used too many words. YMMV.
Here's a very specific case in which I've seen this behavior. It is reproducible for me in IE6 and IE7.
From within an iframe:
window.parent.mySpecialHandler = function() { ...work... }
Then, after reloading the iframe with new content, in the window containing the iframe:
window.mySpecialHandler();
This call fails with "Can't execute code from a freed script" because mySpecialHandler was defined in a context (the iframe's original DOM) that no longer exits. (Reloading the iframe destroyed this context.)
You can however safely set "serializeable" values (primitives, object graphs that don't reference functions directly) in the parent window. If you really need a separate window (in my case, an iframe) to specify some work to a remote window, you can pass the work as a String and "eval" it in the receiver. Be careful with this, it generally doesn't make for a clean or secure implementation.
If you are trying to access the JS object, the easiest way is to create a copy:
var objectCopy = JSON.parse(JSON.stringify(object));
Hope it'll help.
This error can occur in MSIE when a child window tries to communicate with a parent window which is no longer open.
(Not exactly the most helpful error message text in the world.)
Beginning in IE9 we began receiving this error when calling .getTime() on a Date object stored in an Array within another Object. The solution was to make sure it was a Date before calling Date methods:
Fail: rowTime = wl.rowData[a][12].getTime()
Pass: rowTime = new Date(wl.rowData[a][12]).getTime()
I ran into this problem when inside of a child frame I added a reference type to the top level window and attempted to access it after the child window reloaded
i.e.
// set the value on first load
window.top.timestamp = new Date();
// after frame reloads, try to access the value
if(window.top.timestamp) // <--- Raises exception
...
I was able to resolve the issue by using only primitive types
// set the value on first load
window.top.timestamp = Number(new Date());
This isn't really an answer, but more an example of where this precisely happens.
We have frame A and frame B (this wasn't my idea, but I have to live with it). Frame A never changes, Frame B changes constantly. We cannot apply code changes directly into frame A, so (per the vendor's instructions) we can only run JavaScript in frame B - the exact frame that keeps changing.
We have a piece of JavaScript that needs to run every 5 seconds, so the JavaScript in frame B create a new script tag and inserts into into the head section of frame B. The setInterval exists in this new scripts (the one injected), as well as the function to invoke. Even though the injected JavaScript is technically loaded by frame A (since it now contains the script tag), once frame B changes, the function is no longer accessible by the setInterval.
I got this error in IE9 within a page that eventually opens an iFrame. As long as the iFrame wasn't open, I could use localStorage. Once the iFrame was opened and closed, I wasn't able to use the localStorage anymore because of this error. To fix it, I had to add this code to in the Javascript that was inside the iFrame and also using the localStorage.
if (window.parent) {
localStorage = window.parent.localStorage;
}
got this error in DHTMLX while opening a dialogue & parent id or current window id not found
$(document).ready(function () {
if (parent.dxWindowMngr == undefined) return;
DhtmlxJS.GetCurrentWindow('wnManageConDlg').show();
});
Just make sure you are sending correct curr/parent window id while opening a dialogue
On update of iframe's src i am getting that error.
Got that error by accessing an event(click in my case) of an element in the main window like this (calling the main/outmost window directly):
top.$("#settings").on("click",function(){
$("#settings_modal").modal("show");
});
I just changed it like this and it works fine (calling the parent of the parent of the iframe window):
$('#settings', window.parent.parent.document).on("click",function(){
$("#settings_modal").modal("show");
});
My iframe containing the modal is also inside another iframe.
The explanations are very relevant in the previous answers. Just trying to provide my scenario. Hope this can help others.
we were using:
<script> window.document.writeln(table) </script>
, and calling other functions in the script on onchange events but writeln completely overrides the HTML in IE where as it is having different behavior in chrome.
we changed it to:
<script> window.document.body.innerHTML = table;</script>
Thus retained the script which fixed the issue.

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