Auto login to website using script or bookmark - authentication

Question

I've been trying to figure this out using various different methods. I'm trying to create a script/bookmark or some type of quick action to open a browser tab or window with a specific URL, and automatically log me in using my credentials. I'm not all that concerned about security for this at the moment.
At first I figured I'd try to use a javascript bookmark to do this, but nothing I found in my research worked. Next I tried to create a bash script, but I couldn't figure out how to send the credentials in via the terminal. Most recently, I literally copied the source code of a site, created a local file and tried to hack together something where I could prefill the form data with credentials and use JS to submit the form, and I've gotten close with this, but for some reason when I use the JS submit function, it errors out and says that the username and password are invalid. But when i turn off the submit function and manually click "log in" on my local html page, it works as expected. I want this to be a one click process, so the idea of using onload/submit or something to that affect is really important to me.
The site I'm testing with has a Rails backend and my next attempt might be trying to use POST to do what I'm thinking, but that's currently outside of my level of knowledge on the subject.
Anyone answering: i do not want to use a password manager to accomplish this.
My requirement is that i will either be able to a) run a script or b) use a 1-click option to do this per website. Ideally i'd be able to set this up in a sort of programmatic way to do this with multiple sites, but I'd be happy with 1 at the moment.
i know similar questions have been answered before, but I haven't been able to use information from those posts (the ones I've seen anyway) to figure out a good way to do this.

Answer 1

Create a bookmark for the current page you have opened.
Edit the bookmark
Change the value for the URL to something like this.
(javascript:(function(){CODE_GOES_HERE_FROM_BELLOW})();
find the field for username and password on the page.
Given example for hotmail
var inputs = document.getElementsByTagName('input'); for(var i=0;i<inputs.length;i++){if(inputs[i].name === 'passwd'){inputs[i].value = 'YOUR_PASSWORD'}else if(inputs[i].name === 'loginfmt'){inputs[i].value = 'YOUR_USERNAME'}}; document.getElementById(document.getElementsByTagName('form')[0].id).submit();
OR
try out casperjs.

Answer 2

The proposed solution didn't work for me and rather than spending tons of time installing a testing framework that I'll never use other than for this purpose, I decided to try to do this another way.
First, I found out that the reason my JS wasn't working before is because the site did not allow a JS submit to be done, or atleast that's what it seemed to be when I got this error: "Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience"
The javascript I was using was in fact working, just not submitting. I used the following code to fill the fields (using "Class Name" elements on the page since there was no name or ID):
document.getElementsByClassName('username')[0].setAttribute('value', 'user');
document.getElementsByClassName('password')[0].setAttribute('value', 'password');
As I mentioned, the problem was when I tried to use JQuery to submit the form: document.getElementsByClassName('loginForm')[0].submit();
Which is when the above error cropped up. I can't really say for sure whether this is the root of the cause, but the page does submit, but I get an invalid username/password error when I do
I haven't figured out a great way to get around this just yet, but my short-term, "hacky" solution was to use Applescript to send a return keystroke to the browser to submit the form. I'd ideally like to figure out how to get the submission to work using JQuery, but I'm not sure how to get around it.