Chrome - "disable cache" - javascript

I am using Chrome Dev Tools to debug a web app I'm making. I'm curious about this "Disable cache" button in Chrome Dev Tools:
Could someone please tell me what this does?
I've noticed some problems using Offline.js and discovered if I check "Disable cache" here in Dev Tools it works okay.
But what exactly is that doing? I am using Cache Manifest in my app so it works offline, but if clicking "Disable Cache" in Chrome Dev Tools is actually just disguising a bigger problem that's not useful to me.
Essentially what I think is happening:
The image I am loading (see Offline.js - checking while online?) which Offline.js checks for to determine if the user if online or offline, that image is being cached
Hence after the first load, it always appears online
If I disable cache in Chrome Dev Tools, it works correctly because it's loading a fresh copy of the image each time.
Any words of wisdom are welcome.

The disable cache checkbox disable cache, it means every time you connect a server, you will download again the WHOLE website, even already downloaded images.
This may be used when you debug an application that have cache problem (you have cached informations & parsing them but the real data has been changed)

Related

How to get Flask app to refresh after updating JS code without having to clear browsing data

I'm developing a Flask app using flask-socketio, running it with socketio.run(app, debug=True), but every time I update any of the app's Javascript code and then refresh the browser, the changes do not take effect. If I update any of the Python code and then refresh, the Python changes do take effect - the only problem is with Javascript changes.
Clearing my browser's data resolves the issue, but I don't want to have to do that every time I make changes to my JS code. Is there another way?
Try ctrl-clicking (or shift-clicking) the refresh button.
What is likely happening is that the browser is "caching" your Javascript code. Clearing your browser's data clears the cache, and you get the newest updates...
In some browsers, you can avoid doing that by refreshing the page in a way that bypasses the cache. I think the shift-click trick works in Firefox, and ctrl-click is Chrome. Or, look up "bypass cache refresh [browser_name]".
If clearing cache does work, then another method (which I always use) is to keep your developer tools opened and make sure you've checked "Disable cache" in the network tab.
The "Disable cache" feature only works when developer tools is opened as I said.

Mozilla do NOT update source code

I'm developing a website.
I test it in Mozilla,
When I make a change to the website javascript code, I find that the change is not reflected in the browser(I checked code in debugger of Mozilla)
I understand that it's a cache problem because when I clear cache, the things work properly.
Have I identified the issue correctly?
If yes, is there a way to get rid of Clearing Cache every time?
Open the tools (F12). Go to Preferences > Advanced Parameters > Disable cache (when dev tool is open).
This way you only disable cache in dev mode, and have no impact on other sites navigation.
You have an option to disable caching in Preferences.
Go to Preferences->Advanced -> Network and check Override automatic cache management.
Limit it to0.

Open Safari / Google Chrome developer tools programmatically from JavaScript

I'm looking for a way to open the WebKit “developer tools” from a script attached to a web-page. I need solutions for both Google Chrome and Safari, that will open the developer-tools pane if it's not already open, and (hopefully, if you can figure out how) also switch to a particular tab/section of said pane upon opening.
(Use-case, if anyone's interested: I want to open the console.log output-window if there's been an error and a developer is looking at the page; this particular page will be the output of some JavaScript unit-tests.)
I'm setting a bounty on this question because it's obviously one that hasn't been answered to anyone's satisfaction before, and the answer is a hairy one. Please don't answer it unless you have a real answer that both: 1) works in both browsers, and 2) doesn't require private extension APIs that won't work from a static web-page.
See (related, but specific to Chrome, and extensions): Can I programmatically open the devtools from a Google Chrome extension?
Simply: You can't.
The Dev Tools are not sandboxed (unlike any web page), thus granting sandboxed environments the power to open and control an unsandboxed environment is a major security design flaw.
I hope this answers your question :-)
You cannot directly use the Chrome's Dev Tools from your web pages. It is bundled with the browser.
But you can use it like a regular web application. Go to Chrome Developer Tools, then go to Contributing. You will find help on using Dev Tools for your app.
Setting up
Install Chrome Canary on Mac OS / Windows or download the latest Chromium build from the Chromium continuous builds archive on Linux
Clone Blink git repo from https://chromium.googlesource.com/chromium/blink.git
Set up a local web server that would serve files from WebKit/Source/WebCore/inspector on some port (8090)
Running
Run one copy of Chrome Canary with the following command line flags: --remote-debugging-port=9222 --user-data-dir=blink/chromeServerProfile --remote-debugging-frontend="http://localhost:8090/front_end/inspector.html". These flags cause Chrome to allow websocket connections into localhost:9222 and to serve the front-end UI from your local git repo. (Adjust the path to chromeServerProfile to be some writable directory in your system).
Open a sample page (eg www.chromium.org).
Run a second copy of Chrome Canary with the command line flag: --user-data-dir=/work/chromeClientProfile. Open http://localhost:9222. Among the thumbnails you will see the sample page from the other browser instance. Click on it to start remote debugging your sample page.
The DevTools web page that opens is served from the remote-debugging-frontend in the first browser instance, which serves from the git repo your local filesystem. Debug this Devtools Web page and edit its source like any other web app.
I hope this is what you need.
There's no way to control the web developer tool from an in-page script, other than through the Console API which provides mostly logging facilities. Letting scripts control more than that would be a serious security issue, since it would allow a web page to control parts of the browser.
The only API remotely related to what you're trying to do is the debugger command, which switches to the script pane only if the developer tools were already open.
But who are you trying to develop this feature for?
If it's for developers working on the site, then it's better to just use the existing developer tools manually, by setting breakpoints, or the pause on exceptions toggle.
If it's for end users, don't. Unless your site is supposed to be used by highly technical web developers, you're only going to scare away users if the developer tools suddenly pop up with errors.
If you really want to show errors you can implement your own logging framework and the UI for error reporting, which works with basic JS and doesn't depend on a specific browser environment.
here's another answer that proposes a solution to your mentioned use case/objective (detecting errors, getting & displaying console logs) and not the not possible objective in the title.
you can make and use a console wrapper and use it in your code
and/or you can monkey patch the console functions if you use/import external js, but you need to apply it before loading them.
No, Any secure Browser will not allow a script to open an extension, as it leads to insecurity.
But, You may design an Add-On/extension OR Console API's to do the same.. for specific site.
Create an Add-On like this to achieve that requirement.
You can try sending keys 'CTRL' + SHIFT' + 'I'
that may work for Chrome any FireFox (in I.E you need to use 'F12'
I am using it when required as few utils in this add-on use to work better then the built-in.
EDIT:
Now a days Chrome is advanced with many new advancements source.
I hope this helps!
Hate to answer such an old question, but was surprised to not see this as an answer, so I thought I'd add it in case it can help someone in the future.
Assuming you have access to the source code, you can place an alert("open devtools"); statement immediately before the first line you're interested in debugging. This alert will give you an opportunity to open DevTools and set a breakpoint on that first line before clearing the alert thus allowing the code to continue and hitting the breakpoint.

Chrome blocking javascript on localhost

I'm working on developing a site on my local machine (Windows 7 Ultimate x64) using WAMP, running APACHE v2.2.22, PHP 5.3.13, and MySQL v5.5.24. I'm developing using Chrome v 22.0.1229.94. I've got quite a bit of javascript in the site, however, and Chrome is relentlessly blocking javascript from running on the page.
Clicking on the little 'blocked javascript on this page' icon in the address bar includes the dropdown that has "Always allow Javascript on Localhost" checked off, and I also have a JavaScript exception in Chrome's settings explicitly saying to always allow JavaScript on 'http://localhost'.
Cookies are being allowed, "Allow all sites to run JavaScript" is checked off, and I have no idea as to why Chrome is not allowing the JavaScript to run.
Overall, it's not imperative to the project that I figure out a fix as both IE9 and Firefox 16.1 are allowing JavaScript and I can utilize them. I am simply curious if there's anything I can do to fix this in Chrome, as I would like to continue developing in Chrome.
If you notice that JavaScript is only blocked when the console is open (as some are saying), chances are that you disabled JavaScript in the console settings.
Open the console.
Click the vertical ellipsis icon (or the gear icon on older versions) in the upper right and go to settings.
See if the "Disable JavaScript" checkbox is checked.
I have the same issue, but only when the console is open. When the console is closed, JavaScript loads fine on localhost. Makes it hard to debug things though....
I got around it by opening localhost in an incognito window.
You can give your local server a domain name, may be that would help.
Open C:\Windows\System32\drivers\etc\hosts in notepad
Edit that file add a new line at the end
127.0.0.1 mydomain.com
Save, now goto chrome and type in http://mydomain.com/ this should point to your local server.
Since you nolonger run on "localhost" may be chrome will let you pass.
Let's me know if that works. Good luck!

Same Javascript code but not same act

//Edit
Hello.
I have made a website and uploaded to the host. So, the codes what are in my localhost and in the website host are same. Everything works except one JavaScript(jQuery) action(A dropdown menu). On my localhost it works perfect, on the website host, it drops and rises again and than doesn't drop again.
site : http://www.hastahakki.com/index.php?page=anasayfa
The problem on the big buttons like "Doğru Hastane Seçimi" , "Hasta Şikayetleri"
How do I do?
It's rare for pure client code to work differently in a hosted environment provided it is uploaded properly and the same browser is used.
First I would check it's not a cache issue by clearing my browser cache.
Then I would view it in a browser with modern developer tools, which is most browsers with the latest version (Firefox requires the excellent Firebug plugin). In Chrome for instance, looking at the Network output will show you if any resources are failing to load, and the Scripts view will show you any local JavaScript errors that might be triggered by the hosted version.

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