changing from getElementById to querySelector on #1174 issue

[iulianPreuteasa]

Fixes #1174

Make sure these boxes are checked before your pull request (PR) is ready to be reviewed and merged. Thanks!

• [x] PR is descriptively titled 📑 and links the original issue above 🔗
• [ ] tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with grunt test
• [ ] code is in uniquely-named feature branch and has no merge conflicts 📁
• [ ] screenshots/GIFs are attached 📎 in case of UI updates
• [ ] @mention the original creator of the issue in a comment below for help or for a review

We're happy to help you get this ready -- don't be afraid to ask for help, and don't be discouraged if your tests fail at first!

If tests do fail, click on the red X to learn why by reading the logs.

Please be sure you've reviewed our contribution guidelines at https://publiclab.org/contributing-to-public-lab-software

Thanks!

[welcome[bot]]

Thanks for opening this pull request! Dangerbot will test out your code and reply in a bit with some pointers and requests. There may be some errors, but don't worry! We're here to help! 👍🎉😄
One thing that can help to get started is to make sure you've included a link back to the original issue you're solving, in the format fixes #0000 (for example). And to make sure the PR title describes what you're trying to do! (often it can be the same as the issue title) Thanks! 🙌
Then, you can say hello in our chatroom & share a link to this PR to get a review! 👋 ✅

[welcome[bot]]

Congrats on merging your first pull request! 🙌🎉⚡️ Your code will likely be published to https://mapknitter.org in the next few days. Now that you've completed this, you can help someone else take their first step! Reach out to someone else working on theirs on Public Lab's code welcome page (where you'll now be featured as a recent contributor!). Thanks!

Help others take their first step

Now that you've merged your first pull request, you're the perfect person to help someone else out with this challenging first step. 🙌

https://code.publiclab.org

Try looking at this list of `first-timers-only` issues, and see if someone else is waiting for feedback, or even stuck! 😕

People often get stuck at the same steps, so you might be able to help someone get unstuck, or help lead them to some documentation that'd help. Reach out and be encouraging and friendly! 😄 🎉

Read about how to help support another newcomer here, or find other ways to offer mutual support here.