You can do this with the Profile Manager plugin https://community.elgg.org/plugins/385114/

Hi Mario,

yes you could but http://learn.elgg.org/en/1.9/guides/dont-modify-core.html

If you wish to have additional registration fields look at the Profile Manager plugin, it allows you to configure additional profile fields and put those fields on the registration form.

https://community.elgg.org/plugins/1161358/releases/1.1

I don't fully understand what you have done and what exactly you want to achieve. Elgg comes with the "likes" plugin that basically allows liking of any type of content. Have you implemented the like functionality on your own instead? The bundled likes plugin does not jump to the top of the page after liking either. So, if that's what you want why not simply using the bundled likes plugin?

As @iionly mentioned, why reinvent the wheel?

Anyway that sounds like your click event handler does not block further execution ant you get redirected to # (or whatever link you actually use). Try adding return false on the end of the handler function in javascript.