https://reasonml.github.io/en/try.html?rrjsx=true&reason=DYUwLgBA5uAyCWBnMAxATgewLYGUQEM0BjACwgF4JEDizyA+AKAiptOYgB96IApRAHQ4waeADsoAxAAdg8MAAoARADIlASg7cIAQTRp8ATwFgMAfTnIA3I0ahI0wtQCqaYHkKkKEBclESAFQwAIRAUDABXMQATABpWTxJ1CiYWRAB3eS9fNjJtGDAEZHRsD1ouHiKwAQAzcWjfEXEoINDwqOiKvkFhf0lkQjBEAHV5JOSAby0IeRAsFJmwOa7+ISaJATQQWXwiEEa+1rDImPilDWmQAA896TB4…

parseSearch.re

let getListFromSearch = search =>
  search
  |> Js.String.split("&")
  |> Array.to_list;

let parseUrlSearch = (stringToBeFound, search) =>
  switch (search |> getListFromSearch |> List.find(stringToBeFound |> Js.String.startsWith)) {
  | item => item |> Js.String.replace(stringToBeFound, "")
  | exception Not_found => ""
  };

let emailString = "email=";
Js.log("foo&[email protected]&displayModal=1" |> parseUrlSearch(emailString));