Replace .click(), .focus() and .attr() jQuery functions with equivalent native JS

[dheerajdlalwani]

I have tested the changes in Edge Chromium, Chrome, Firefox and IE 11.

So far everything has been working. Opening PR. Let me know if any changes are required :)

Fixes #919 .

[Jaifroid]

Thank you very much for this PR. It's looking good! I haven't tested yet -- I've got some minor changes, mostly to do with quotation mark style, and a few cases where you could convert some other functions as well which don't look difficult to do. I'll test once you've made changes.

[dheerajdlalwani]

Thank you very much for this PR. It's looking good! I haven't tested yet -- I've got some minor changes, mostly to do with quotation mark style, and a few cases where you could convert some other functions as well which don't look difficult to do. I'll test once you've made changes.

Sure! I'll make the changes.

[Jaifroid]

Nearly there -- just a few more small things!

[Jaifroid]

This looks good, thanks (there is just one minor thing, removing a blank line). I'll do some testing later today, in particular on the effect of purging the iframe.

[dheerajdlalwani]

This looks good, thanks (there is just one minor thing, removing a blank line). I'll do some testing later today, in particular on the effect of purging the iframe.

Great. I've removed the empty line. And sure, do test and let me know if there are any issues. I'll be most happy to resolve them :)

[dheerajdlalwani]

I tested your suggestion, @Jaifroid and it works flawlessly! Thank you so much. Let me know if anything else is required.

Here, take a look!

[Jaifroid]

@dheerajdlalwani Thank you very much, and also for testing thoroughly. It looks good now! I presume you don't see a button "Squash and merge" below the test results below? If you don't see it, or can't click it, let me know if you are ready to squash/merge, and I'll do it -- it will still appear on GitHub as your contribution/merge. NB it is important to squash down to a single commit, but GitHub can do this automatically.

[dheerajdlalwani]

Thank you so much, @Jaifroid. No, I don't see the Squash and Merge button. I think you will have to do it. And you don't have to thank me! It was absolutely my pleasure. I'm learning so much from this! Infact, I am enjoying it!