[Vuejs]-How to change text in sidebar dynamically based on component I click on?

First of all you should consider migrating your helper to vuex, using store features will help you in every thing.

You will have all intervals in one array and, for instance, have a prop in your store for currentInterval that changes every time you click an interval on the timeline. You can achieve this by dispatching a vuex action to the store that will mutate the state of your prop, ex currentInterval.

In the component where you show the current interval data you will …mapGetters from the store that will always return that prop currentInterval of the store.

More information about store management here: enter link description here