Editing Javascript using Chrome Developer Tools - javascript

I am trying to edit javascript on a site using Chrome's Developer Tools. I have read about 30 accounts of how to do this as well as watched a few videos. The fact is, when I go to the sources tab and open the file I want to edit, I can't do anything to it. Is there some step I am missing?
I can create break points, step through, etc... I just can't edit. Was this functionality removed recently?

I know this question is stale, but I just had a similar problem and found the solution.
If you have the file prettified, Chrome will not allow edits. I turned it off and was able to edit. Willing to bet this is/was your problem.

You can edit javascript in the developer tools on the "Sources" tab, BUT it will only allow you to edit javascript in its own file. Script embedded in an HTML (or PHP) file will remain read-only.

It has some limitations:
has to be a JS file. can't be embeded tags in a html page.
it cannot be prettified.

I don't know if you need this to save permanently, but if you need to just temporarily modify the js:
I can copy that javascript I want to modify into a text editor, edit it, then paste it in the console and it will redefine any functions or whatever that I need to be redefined.
for instance, if the page has:
<script>
var foo = function() { console.log("Hi"); }
</script>
I can take the content between the script, edit it, then enter it into the debugger like:
foo = function() { console.log("DO SOMETHING DIFFERENT"); }
and it will work for me.
Or if you have like,
function foo() {
doAThing();
}
You can just enter
function foo() {
doSomethingElse();
}
and foo will be redefined.
Probably not the best workaround, but it works. Will last until you reload the page.

I did search "chrome dev tool edit javascript". This page is the first search result. But it is too outdated, it does not help me.
I am using Chrome 73, this version of Chrome has "Enable Local Overrides" option. Using the function, I could edit a javascript and could run and debug.

My solution:
In the devtools preferences check the Enable local overrides.
Go to network tab, find the file you want to edit, rigth click on it and select Save for overrides (on the sources/overrides tab you need to add a local folder)
The file appears in a new tab on the Sources tab as local copy, so you can edit this file, and after site reload the new (and edited) override file will load on the site!

Related

On the Wix Velo platform, is code placed in the "Page" area publicly visible?

According to this article, code that is put in the Page area specifically is publicly accessible. They even include this image to demonstrate:
I have not been able to see code that is entered here on the published version of the site. Here is an example where I published a blank page with a code in the onReady function:
https://steven0790.wixsite.com/my-site/blank
When I go to this page and inspect and search, I can't find the code. I would expect it to be in a <script> tag.
I have also tried looking through links in the code in case this is saved in a .js file or something like that.
Can anyone confirm whether or not this code really is accessible?
Check the Console instead of the Elements tab in the browser developer tools. It will let you know which JS file contains your code.
Look for a message that looks something like this:
Running the code for the HOME page. To debug this code in your browser's dev tools, open cnric.js.
You can then open that file in your browser developer tools and see the code.

Editing the source of a minimised javascript

I'm new to Javascript and web development, but I've been writing iOS software for the past 7 years. I'm not a complete noob.
Here's the issue I'm having. I'm having a minimised Javascript file which is inserted in the website on the internet. How can edit the original source, while testing this on the website online where the bug in the Javascript is appearing.
Google Chrome appears to have a function like that, but I can't seem to make it work. Any tips, resources or explanation so I can get this thing figured out?
Thanks.
Yes, Chrome has "overrides" function which allows this.
Step 1: enable overrides
F12 > Sources > Overrides (in the left tab) > Enable Local overrides
You'll need to provide a path for it to save the scripts
Step 2: go
F12 > Sources > Network > Locate the relevant JS file > right-click > save for override
Go back to Overrides, navigate to the file and edit it. CTRL+S to save, then F5 to reload. Since you have the original javascript, you might as well replace the minified source with the original in the override.
Try this one.
Unminify JS
PS use KOALA for the minification of your CSS/JS.
Koala

Using Google Chrome to debug and edit javascript embedded in HTML page

Chrome developer tools allows you to edit javascript in the browser if the javascript is in a .js file. However, it does not seem to allow me to edit javascript that is embedded in an HTML page. ie:
<script type="text/javascript>
// code here that I want to debug/edit
</script>
This is a big problem for me as I have quite a bit of embedded javascript in a certain page.
Similar to this question: Edit JavaScript blocks of web page... live but this is about firefox, not chrome.
How can I edit javascript embedded in an HTML page using Google Chrome Developer Tools?
Actually chrome allows to do that, choose HTML files in Sources tab in Developer tools window. You will see HTML instead of javascript and simply add breakpoints in the <script> tags. Also you can add debugger; command to script what you want to debug. For example:
<script>
// some code
debugger; // This is your breakpoint
// other code you will able to debugg
</script>
Don't forget to remove debugger;'s when you want to release your website.
I had a difficult time locating the file that had my inline/embedded javascript. For others having the same problem, this may or may not be helpful...
Using Chrome 21.0.1180.89 m for Windows
All files are shown after clicking that very discreetly placed button. See:
Now you may begin debugging...
None of these answers have worked for me.
What works for me is if I have my javascript on the page already loaded, I can copy that javascript, edit it, then paste it in the console and it will redefine any functions or whatever that I need to be redefined.
for instance, if the page has:
<script>
var foo = function() { console.log("Hi"); }
</script>
I can take the content between the script, edit it, then enter it into the debugger like:
foo = function() { console.log("DO SOMETHING DIFFERENT"); }
and it will work for me.
Or if you have like,
function foo() {
doAThing();
}
You can just enter
function foo() {
doSomethingElse();
}
and foo will be redefined.
Probably not the best workaround, but it works.
Go to the Elements tab, find your script, right click on the part you need and choose "Edit as HTML".
If Edit as HTML doesn't appear, double click the node and it should become highlighted and editable.
Solution described here: https://greatrexpectations.com/2014/01/22/chrome-dev-tools-inline-dynamic-javascript
Add the 'sourceURL' directive in your inline/embedded script like this:
<script type="text/javascript">
...script here...
//# sourceURL=helperJavaScript.js
</script>
Then this script will appear in the page Sources and you can debug and edit it similarly to js loaded from a URL source

Easier way of testing and adding Javascript to a page in Firefox?

I am trying to extend some Javascript in one of my pages and for quick "will this work" code it's a huge pain. Basically it consists of editing code in my IDE and save, switch to Firefox, reload page, set breakpoint in Firebug, examine and repeat
Are there any Firefox extensions that will aid me in this respect?
The only thing I can find is using javascript: ... in the address bar, but that's a huge pain, can only hold a single line, and there is no way of making the test code persist across a page reload.
Try jsfiddle.net. You can experiment with html, css and code within your browser and debug that with firebug for example. You can use a diversity of js-frameworks (or none), simulate XHR, and add your own (js/css)resources. It's not ideal, but much better than the practice you described.
You can also try using KomodoEdit, which offers 'view in browser' functionality, even for URLS and with a preset browser.
just use the js console that comes with firebug. You can write all manner of code in there and even declare functions and variables that can be referenced. if you need more than one line, firebug can do that too.
EDIT: except page reload.... if you need to do page reload it needs to be saved somewhere. I would use a Greasemonkey script
You can use the Web Console (new in Firefox 4 and higher) - press Ctrl-Shift-K to open it for a particular page. The command line is at the bottom, press Shift-Enter on the command line to enter more than one line.

JavaScript file not updating no matter what I do

I have an external JavaScript file and whether in FireFox or Chrome, whether all browsing data is cleared, it will NOT update no matter what. I believe something happened when I made a backup of my file, which I simply added "_thedate" to the end of the name. Then Save As back to the original name.
Now I cannot seem to get rid of the old JS no matter what unless I change the name of the file, which I really don't want to do, or add the script to the PHP page, which crowds it.
Anyone know the solution to this?
You are sure you are linking to the same file and then editing that same file?
On some browser, you can use CTRL F5 to force a refresh (on the PC). On the Mac, it is Cmd Shift R
Firebug also has a net tab with "Disable Browser Cache".
But I want to give a warning here: even if you can hard refresh, how do you know your customers are getting the latest version? So you need to check, rather than just making sure you and your program manager can do a hard refresh and just go home and take the paycheck next month. If you want to do a job that change the world for the better, or leave the world a little bit better than you found it, you need to investigate more to make sure it works for your customers too (or else, sometimes the customer may call tech support, and tech support may read the script of "clear out the cookies and it will work", which is what happens to me sometimes). Some methods down at the bottom of this post can ensure the customers get the latest version.
Update 2020:
If you are using Chrome and the DevTools is open, you can click and hold the Refresh icon in front of the address bar, and a box will pop up, and you can choose to "Hard Reload" or even "Empty Cache and Hard Reload":
Update 2017:
If you use the Google Chrome debugger, it is the same, you can go to the Network section and make sure the "Disable cache (while DevTools is open)" is checked, in the Settings of the debugger panel.
Also, when you link the JavaScript file, use
<script src="my-js-file.js?v=1"></script>
or v=2, and so forth, when you definitely want to refresh the file. Or you can go to the console and do a Date.now() and get a timestamp, such as 1491313943549, and use
<script src="my-js-file.js?t=1491313943549"></script>
Some building tools will do that automatically for you, or can be configured to do that, making it something like:
<script src="main.742a4952.js"></script>
which essentially will bust the cache.
Note that when you use the v=2 or t=1491313943549, or main.742a4952.js, you also have the advantage that for your users, they definitely will get the newer version as well.
How about adding a '?2' to the tag?
<script src="a.js?2"></script>
The server should return the same file with or without the '?2', but the browser should see it as a different file and redownload. You can just change this query string whenever the file is changed.
adapted from: http://blog.httpwatch.com/2007/12/10/two-simple-rules-for-http-caching/
I've had this problem before, it's very frustrating but I found a work around. Type in the full address of the js file (i.e. yourhost.com/javascript.js) and load it. You will probably see the old version load. Then hit f5 to refresh that page and you should see the new version load. The js file will now be updated in your cache and the code should run as you expect.
The solution I use is.
Using firefox
1. using web developer --> Web Console
2. open the java-script file in new tab.
3. Refresh the new tab you should see your new code.
4. Refresh the original page
5. You should see your changes.
I had this problem and solved in Chrome by just disabling Cache:
- Click F12;
- Go at Network tab;
- Click on "Disable Cache".
A little late to the party, but if you put this in your html, it will keep your website from updating the cache. It takes the website a little longer to load, but for debugging purposes i like it. Taken from this answer: How to programmatically empty browser cache?
<meta http-equiv='cache-control' content='no-cache'>
<meta http-equiv='expires' content='0'>
<meta http-equiv='pragma' content='no-cache'>
Rename your js file to something else temporarily. This is the only thing that worked for me.
The best way around browsercaches is to append a random number to the path of the js file.
Example in pseudo code:
// generate a random number
int i = Random.Next();
echo "<script src='a.js?'" + i + "></script>";
This will make sure your browser always reloads the file, because it thinks it's a different file because of the random number in the url.
The server will always return the file and ignore what comes after the '?'.
In both Firefox and Chrome, that is really annoying, but because of their default settings which can be changed the following way and then they work. I tried in Chrome and Firefox both with same order of steps.
Press F12 (Open Inspector)
Click Network, and then click Disable Cache
Now click Clear icon. In Firefox, it shows as a trash bin icon on left corner, in Chrome it is the second left icon, in between 'stop recording' and 'Filter'.
Now press F5 or refresh the page
They do update the resources with their fresh copy as they re-download them.
In Asp.netcore we can use asp-append-version taghelper
<script src="~/js/site.js" asp-append-version="true"></script>
Are you 100% sure your browser is even loading the script? Go to your page in Firefox and use the console in Firebug to check if the script has been loaded or not.
I have the same problem for awhile, and manage to figure out... And my case was because I have 2 javascript with the same function name.
1.Clear browser cache in browser developer tools
2.Under Network tab – select Disable cache option
3.Restarted browser
4.Force reload Js file command+shift+R in mac
 
Make sure the fresh war is deployed properly on the Server side
I was going insane trying to get my js files to refresh and I tried everything. Then I did a header check and remembered I was using Cloudflare!
In Cloudflare you can use dev mode to disable proxy.
Don't forget to check any errors in webpack compilation. Sometimes the application.js in app/javascript/packs/ doesn't reload due to webpack compilation error.
When I run into this issue I try this sequence of steps:
Hard refresh the page.
Clear cache + cookies.
Add a static version to my script.
src="my-script-name.js?v=1"
If the above does not help, add a dynamic version to my script:
src="my-script-name.js?v=" + Date.now() + Math.random()

Categories

Resources