Firebase prefixed case sensitive query

queryByPrefix.ts

import type firebase from "firebase";

function findUpperBound(s: string): string {
  if (!s.length) {
    return s;
  }
  const c = String.fromCharCode(s.charCodeAt(s.length - 1) + 1);
  return s.substring(0, s.length - 1) + c;
}

export function queryByPrefix(
  query: firebase.firestore.Query<firebase.firestore.DocumentData>,
  field: string,
  prefix: string
): firebase.firestore.Query<firebase.firestore.DocumentData> {
  return query
    .where(field, ">=", prefix)
    .where(field, "<", findUpperBound(prefix))
    .orderBy(field, "asc");
}