My search feature in react doesn’t work properly

I made a react js website that using crypto api and My search feature on website works but the result show up just for a moment.

functions for search feature :
(https://i.sstatic.net/MBnoaP7p.png)

the body of my website :
(https://i.sstatic.net/19JjFRB3.png)

When i search, it shows result for a second !
Do you know problem ? I can’t find problem that cause this thing.