Products with unit variable cost

Question

Hi
I want to add a part to my website for selling Likes(instagram like for instance).
How can I make it that customers see the price automatically by typing the number of likes they want into the related blank?
for example this website
https://www.instafollowers.co/buy-instagram-likes

Answer 1

if(like == 200){
cost = 500;
}eslenif(like == 400){
cost = 1000;
}

you can use if else statement

Answer 2

I think you can do something like
var cost=0.001$
var NumberOfLikes=prompt("to let the user type the number he wants " )

var FinalCost=cost*NumberOfLikes