How can I make a system that will check whether the text I write in the textbox exists in the sheets?

Question

I have a very simple question because I am very new and trying to learn. I want to create a text box on my own website and write a system that checks whether what is written in that box is in google sheets and says to the user whether it exists or not.

I dont know where should i start.

Answer 1

It's just an example but and you can change it in the way you want.

let mainData = "this is our main string data...";
let inputString = "this in my entered val";
        
        
let result = mainData.includes(inputString);