Google Chrome editing Javascript on the fly - javascript

I've tried to ease my life by using Google Chrome's devtools and as I've tried to modify javascript of page on fly but it seems to behave unexpectedly
I have this function that is called every frame of the game
View.prototype.onHit = function() {
for(var i = 0; i < this.obstacles.length; i++) {
if(this.obstacles[i].dealsDamage) {
//deal damage
} else {
//do something else
}
}
}
and when I open it on chromes "Sources tab" and pause execution and add something simple such as
console.log("hey");
it starts printing text "hey" on console as expected but the moment i modify some code such as the if check to
if(!this.obstacles[i].dealsDamage) {
//do something else
} else {
//deal damage
}
inverting the behaviour and save the document, the code doesnt take effect and the logging source changes to View.js (old)
and anything I change after that doesn't affect the running javascript

The "(old)" script normally should only appear if the more complex changes are applied. Namely, if you change a function parameter number or start (and lamently stop) using a variable from outer scope.
If live edit fails to work in such simple use-case as you describe, it could be a good thing to file to http://crbug.com

Related

Using the Notification API from a bookmarklet

I am trying to write a bookmarklet that sends me a desktop notification when CI on GitHub completes. Notification.requestPermission runs correctly, and asks me for permission, and the console.log statements run correctly, but the notification does not appear. Here is the text of the bookmarklet script:
(function() {
Notification.requestPermission().then(() => {
const search = setInterval(() => {
if (window.find("All checks have passed")) {
console.log('all checks passed');
clearTimeout(search);
new Notification('Github checks passed!');
} else {
console.log('checks pending');
}
}, 1000);
});
})();
i.e.
javascript:(function() {Notification.requestPermission().then(() => {const search = setInterval(() => {if (window.find("All checks have passed")) {console.log('all checks passed');clearTimeout(search);new Notification('Github checks passed!');} else {console.log('checks pending');}}, 1000);});})();
Is this a sandboxing thing?
I have tried with the same code you have written and tried to add few tweaks and verify the existing code.
I have seen that there not an issue with your code. I have tried to simulate the same situation with your code and it works.
In order to work on your code, I have added dummy text in the HTML body after 5 seconds of page loads, meanwhile, setTimeout function logs checks pending
After 5 seconds it a text in the body and after that it goes to search the text and the code works fine.
Here my little tweaks which might help you to identify the root cause. I guess if your code is working on these tweaks, it means that somehow in your real situation the text might not found from the HTML template.
Yes, one more thing you should keep in mind that you must allow notification when the browser asks in popup, Once you allow the show the notification, in the next attempt it will populate the notification with suggested text.
Following code, I have tried.
minify version:
javascript:(function(){Notification.requestPermission().then(()=>{let e=0;console.log("find:",window.find("All checks have passed"));const n=setInterval(()=>{if(window.find("All checks have passed"))clearTimeout(n),new Notification("Github checks passed!");else{if(5===e){const e=document.createElement("label");e.innerHTML="All checks have passed",document.body.appendChild(e)}console.log("checks pending")}e+=1},1e3)})})();
beautify version:
javascript: (function() {
Notification.requestPermission().then(() => {
let counter = 0;
console.log("find:", window.find("All checks have passed"));
const interval = setInterval(() => {
if (window.find("All checks have passed")){
clearTimeout(interval);
console.log("checks passed");
new Notification("Github checks passed!");
} else {
if (5 === counter) {
const el = document.createElement("label");
el.innerHTML = "All checks have passed";
document.body.appendChild(el);
}
console.log("checks pending");
}
counter += 1;
}, 1000)
})
})();
I have also attached the screenshots for your reference.
For your reference, this code will work in the console also it will populate the message in your console also.
Hope it might clear your idea.
This code is 100% working, so if you still face the trouble, let me know I will definitely try to help you.
As others have said, the code works as expected.
My guess is you're having problems with the setInterval function. On firefox, setInterval doesn't run when the tab isn't on focus (you also lose focus when you execute the bookmarklet from the bookmark tab).
I assume you navigated to a different tab which results in the timer stopping. Unfortunately I don't think there's an easy solution to get the result you want.
See here for reference: SetInterval not running in Firefox when lost focus on tab/window

document.getElementById always returns "null" for ribbons

I need to set the background color of one of the buttons in the form's ribbon. This isn't supported through Ribbon Workbench, so I have written following javascripts to achieve the same:
function setOpportunityRibbonsAppearance() {
var submitToForeCastButton = parent.document.getElementById("opportunity|NoRelationship|Form|sfw.opportunity.Button1.Button");
if (submitToForeCastButton != null) {
submitToForeCastButton.style.backgroundColor = "lightyellow";
}
}
I have registered this scripts in Form Load event. However the issue is that, I always get parent.document.getElementById as null only.
Surprisingly, I am able to see the control while running the parent.document.getElementById statement in the browser's console, and can also change the styling attributes.
Can anyone please suggest what could be wrong here?
P.S. - I understand document.getElementById is not recommended to use in CRM, however, I am left with no other choice while trying to change the appearance of some of the buttons.
Any help on this, will be much appreciated.
You could upload an icon with a yellow background, to keep everything supported. You won't see text on yellow but it might work for you. Easy and standard.
To keep it unsupported and ugly, you could just keep on trying until you make it, setInterval allows for a function to be repeated:
function setOpportunityRibbonsAppearance() {
var submitToForeCastButton = null;
var interval = setInterval(function(){
submitToForeCastButton = parent.document.getElementById("opportunity|NoRelationship|Form|sfw.opportunity.Button1.Button");
if(submitToForeCastButton != null) {
submitToForeCastButton.style.backgroundColor = "lightyellow";
clearInterval(interval);
}
}, 500); // Every 500ms. Adjust as needed, not too fast or browser will choke.
}
Its probably because your script is running before the page is fully loaded.
Try adding a delay to the to the function Put a Delay in Javascript

Why does waitForKeyElements() only trigger once despite later changes?

For several years I've used the waitForKeyElements() function to track changes in webpages from a userscript. However, sometimes I've found it doesn't trigger as expected and have worked around out. I've run into another example of this problem, and so am now trying to figure out what the problem is. The following is the barest example I can create.
Given a simple HTML page that looks like this:
<span class="e1">blah</span>
And some Javascript:
// function defined here https://gist.github.com/BrockA/2625891
waitForKeyElements('.e1', handle_e1, false);
function handle_e1(node) {
console.log(node.text());
alert(node.text());
}
setInterval(function() {
$('.e1').text("updated: "+Math.random());
}, 5000);
I would expect this code to trigger an alert() and a console.log() every 5 seconds. However, it only triggers once. Any ideas?
Here's a codepen that demonstrates this.
By design and default, waitForKeyElements processes a node just once. To tell it to keep checking, return true from the callback function.
You'll also want to compare the string (or whatever) to see if it has changed.
So, in this case, handle_e1() would be something like:
function handle_e1 (jNode) {
var newTxt = jNode.text ();
if (typeof this.lastTxt === "undefined" || this.lastTxt !== newTxt) {
console.log (newTxt);
this.lastTxt = newTxt;
}
return true; // Allow repeat firings for this node.
}
With the constant string comparisons though, performance might be an issue if you have a lot of this on one page. In that scenario, switching to a MutationObserver approach might be best.

In a Firefox restartless add-on, how do I run code when a new window opens (listen for window open)?

I am starting to build a restartless Firefox add-on and I am having trouble setting up the bootstrap.js. Everyone seems to agree that the core of a bootstrap.js is pretty much boilerplate code, along these lines:
const Cc = Components.classes;
const Ci = Components.interfaces;
function startup() {
let wm = Cc["#mozilla.org/appshell/window-mediator;1"].getService(Ci.nsIWindowMediator);
let windows = wm.getEnumerator("navigator:browser");
while (windows.hasMoreElements()) {
let domWindow = windows.getNext().QueryInterface(Ci.nsIDOMWindow);
// then can control what happens with domWindow.document
}
}
function shutdown() {}
function install() {}
function uninstall() {}
This code works and I can control things in the existing windows. For example, domWindow.alert("text") successfully creates a standard alert saying "text" on every window that is currently open.
However, I can't find any code that will allow me to do things in new windows; i.e. those created after the script runs. What is the correct way to handle the creation of new windows and gain control over them, to the point where I could get another "text" alert from one when it is created?
Edit: Using the nsWindowMediator class and the code sample from MDN, I now have this:
var windowListener = {
onOpenWindow: function (aWindow) {
try {
let domWindow = aWindow.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowInternal || Ci.nsIDOMWindow);
domWindow.addEventListener("load", function () {
domWindow.removeEventListener("load", arguments.callee, false);
//window has now loaded now do stuff to it
domWindow.alert("text");
}, false);
} catch (err) {
Services.prompt.alert(null, "Error", err);
}
},
onCloseWindow: function (aWindow) {},
onWindowTitleChange: function (aWindow, aTitle) {}
};
function startup(aData, aReason) {
// Load into any existing windows
try {
let wm = Cc["#mozilla.org/appshell/window-mediator;1"].getService(Ci.nsIWindowMediator);
let windows = wm.getEnumerator("navigator:browser");
while (windows.hasMoreElements()) {
let domWindow = windows.getNext().QueryInterface(Ci.nsIDOMWindow);
loadIntoWindow(domWindow);
}
} catch (err) {
Services.prompt.alert(null, "Error", err);
}
Services.wm.addListener(windowListener);
}
However, there is still no output from the onOpenWindow call - the "text" alert does not appear, nor does the error alert in the catch block. I can confirm that onOpenWindow is actually being entered; if I put a Services.prompt.alert() at the beginning of onOpenWindow, I get the alert when I create a new window. Unfortunately, I get an infinite loop of alerts and I have no idea why.
However, I can't find any code that will allow me to do things in new windows; i.e. those created after the script runs. What is the correct way to handle the creation of new windows and gain control over them, to the point where I could get another "text" alert from one when it is created?
The correct way to act on each window when it opens is to use addListener() from nsIWindowMediator. The example code below does this. The nsIWindowMediator is included in Services.jsm and is accessed through Services.wm.addListener(WindowListener). In order to use a window listener, you have to pass it an nsIWindowMediatorListener (ref2) object. An nsIWindowMediatorListener contains three keys: onOpenWindow, onCloseWindow, and onWindowTitleChange. Each should be defined as a function which will be called when the appropriate event occurs.
The MDN document How to convert an overlay extension to restartless in "Step 9: bootstrap.js" contains an example of a basic bootstrap.js which will run the code in the function loadIntoWindow(window) for each currently open browser window and any browser window which opens in the future. I have used code modified from this in a couple of different add-ons. The example is substantially similar to the code you are already using. The example is (slightly modified):
const Ci = Components.interfaces;
Components.utils.import("resource://gre/modules/Services.jsm");
function startup(data,reason) {
// Load this add-ons module(s):
Components.utils.import("chrome://myAddon/content/myModule.jsm");
// Do whatever initial startup stuff is needed for this add-on.
// Code is in module just loaded.
myModule.startup();
// Make changes to the Firefox UI to hook in this add-on
forEachOpenWindow(loadIntoWindow);
// Listen for any windows that open in the future
Services.wm.addListener(WindowListener);
}
function shutdown(data,reason) {
if (reason == APP_SHUTDOWN)
return;
// Unload the UI from each window
forEachOpenWindow(unloadFromWindow);
// Stop listening for new windows to open.
Services.wm.removeListener(WindowListener);
// Do whatever shutdown stuff you need to do on add-on disable
myModule.shutdown();
// Unload the module(s) loaded specific to this extension.
// Use the same URL for your module(s) as when loaded:
Components.utils.unload("chrome://myAddon/content/myModule.jsm");
// HACK WARNING: The Addon Manager does not properly clear all add-on related caches
// on update. In order to fully update images and locales, their
// caches need clearing here.
Services.obs.notifyObservers(null, "chrome-flush-caches", null);
}
function install(data,reason) { }
function uninstall(data,reason) { }
function loadIntoWindow(window) {
/* call/move your UI construction function here */
}
function unloadFromWindow(window) {
/* call/move your UI tear down function here */
}
function forEachOpenWindow(todo) {
// Apply a function to all open browser windows
var windows = Services.wm.getEnumerator("navigator:browser");
while (windows.hasMoreElements())
todo(windows.getNext().QueryInterface(Ci.nsIDOMWindow));
}
var WindowListener = {
onOpenWindow: function(xulWindow) {
var window = xulWindow.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIDOMWindow);
function onWindowLoad() {
window.removeEventListener("load",onWindowLoad);
// Only add UI changes if this is a browser window
if (window.document.documentElement.getAttribute("windowtype")
== "navigator:browser")
loadIntoWindow(window);
}
window.addEventListener("load",onWindowLoad);
},
onCloseWindow: function(xulWindow) { },
onWindowTitleChange: function(xulWindow, newTitle) { }
};
While there is quite a bit more that your might want to do in your bootstrap.js code, the above is organized reasonably well and keeps all of the code to load into the Firefox UI within loadIntoWindow(window) and unloading the UI within unloadFromWindow(window). However, it should be noted that some UI elements you should only be adding/removing once (e.g. australis widgets, like buttons) and other elements (e.g. direct changes to the Firefox DOM) have to be added once in each window.
Unfortunately, I get an infinite loop of alerts and I have no idea why.
One of the significant differences between this example and what you are currently using is the test for the type of window that has opened. This is done so that we are only acting on newly opened windows which are browser windows instead of all newly opened windows:
if (window.document.documentElement.getAttribute("windowtype") == "navigator:browser")
loadIntoWindow(window);
The problem you describe of getting an infinite loop of alert() popups is caused by not checking to make sure that you are only acting on browser windows. The alert() popup is a window. Thus, you are calling alert() for every alert() window you open which, of course, just opens another alert() window on which you call alert(). This is your infinite loop.
Additional references:
1. Working with windows in chrome code
However, I can't find any code that will allow me to do things in new windows
When working with XPCOM objects you generally want to study their interfaces, which are often found on MDN. In this case your starting point would be nsIWindowMediator, since that's the service you're using in line 5.
As you can see it has an addListener function, which takes a parameter implementing nsIWindowMediatorListener. There's a code-example right there on the page.
But let's assume for the moment there isn't a code example. You could search for the interface on MDN, but it isn't listed. The next step would be searching MXR for the .idl. idl = interface description language
Once you got the interface contract you can more or less just implement it in javascript, at least for listeners. Implementing your own xpcom services would be a little more complicated.
Searching the addon sdk can often provide some hints too. In this case they don't seem to be using .addListener, but the file hints at another interesting service, which in turn you can find on MDN: nsIWindowWatcher.
Basically, if you're writing restartless addons you're rummaging through the entrails of firefox and will have to do some detective work to find the exact components you need. If you want something more convenient I would recommend the addon sdk, which provides a more organized but also more restricted set of commonly used APIs

Java Script error - can't convert undefined to object

I get "can't convert undefined to object" error while trying to run this piece of code. I'm not a programmer and can barely code therefore my question might be quite stupid/unanswerable for what I'm deeply sorry.
Code:
if (path == F[0])
{
//go N
if (pointAy > 0)
{
if (!(PS.BeadData(pointAx, pointAy - 1) === "blocked"))
{
// Set bead to Previous State
PS.BeadColor(pointAx, pointAy, previous_bead_NPC[NPCid][2]);
PS.BeadData(pointAx, pointAy, 0);
PS.BeadGlyph(pointAx, pointAy, " ");
// Increment
pointAy -= 1;
// Place NPC
MakeNPC(pointAx, pointAy, NPC[NPCid][2], NPC[NPCid][3], NPC[NPCid][4], NPC[NPCid][5], 1);
}
}
}
Can't really tell if this is enough to find an answer for you - I can post more of the code if it would help.
Maybe there is some generic answer to such an error a normal programmer would know, but such a noob like me will be oblivious to?
UPDATE
Ok, through step-by-step execution I found out that the error pops out in a different function even though disabling above piece of code makes the error not pop up. This is the function that makes the error pop up:
PS.Tick = function ()
{
"use strict";
for (var NPCid = 0; NPCid < 10; NPCid++)
{
NPCAI(NPCid);
};
};
This function is called every second and it calls AI logic function to move 10 NPC on a grid by supplying the NPCid to the AI function. Script fails here, but not always - usually one or two of the NPCs makes a step and only then the function fails.
If you are using Chrome or Firebug you can step through the JavaScript code. On Chrome, open up the tools icon (wrench in the upper right corner), then enable the developer tools by selecting "Tools" from the drop down menu and the "Developer Tools". At the bottom you should see a button in the lower part of your screen for scripts. Click on that and navigate to your page. When you see your JavaScript file open it and put a breakpoint at the "if" statement. Reload your page and then look at the values of PS and NPC when the debugger stops your code.

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