JSFiddle - React, Tailwind, and code Playground

JavaScript

var db ={
  a: 1,
  b: 2,
  c: 3
};

var next = function(db, key) {
    var keys = _.keys(db);
    var index = _.indexOf(keys, key);
    if(index+1<keys.length){
         return db[keys[index+1]];
    }else{
        return null;
    }
};

console.log(next(db, 'a'));