If you are a developer who deals with code then you are either amongst those lucky people working for Google labs or you are very likely to deal with legacy line of business code on a daily basis. Despite the fancy tech talk after your sucessful fizz-buzz bullshit where the guys wanted you to write technical test too top on an in depth conversation around React and some recent Redux stuff which includes immutability and React Router, Context, Relay - they can be a little bit surprised when you are throwing them the question on your second day - why the heck are we using 5 years old JS code with jQuery? The answer is probably they have been told to maintain legacy nightmare for now and also to going away from this code soon. You are trapped. Why??! Consider this from a business point of view. If your company selling clothes online and you convert their already working Backbone code (the whole framework is a huge anti pattern OMG BTW) in to fancy immutable React Redux unicorn - how much money they can save? Probably nothing much or if slightly more than nothing - is nothing to do with your code re write. However you can always improve things, make them faster etc.
What (business) people are paying for?
UX with A/B testing If you can manage to create user experience - user journey that increases conversion and revenue then you are in a good position to do slight improvements and proving them by numbers. Going step by step and backed by statistics. Devops optimizations If you can find patterns in the daily usage of resources or you can optimize the daily workflow then you are saving money to your company and I can not see the point not to do so unless a very political environment that is too slow to move (e.g. from self hosted to AWS). Code quality and integrity Unit tests. Easy to sell. Do it. Code reviews, Git worflow or pull request - try it - nothing to lose here.
What business usually does not buy
Complete rewrite Rewriting ugly code just for the sake of it. Even when technology is emerging - you have to make a very strong point to convince an organization that commited spend money wisely on a complete code refactoring. Unless the code was that much bad and unmaintanable or resources had become recently too expensive and difficult to find (let’s say that is a C++ legacy system) then you probably can not do it. Fancy a complete NodeJS microservice backed React stack? The good news is that you very likely to find a team, bad news is not going to be that much cheaper due to the high demanding and bids of full stack front end engineers.
What start ups usually buy
Are you fancy of a recent Angular or React stuff? - But be careful here Start ups are mostly the only places on Earth where someone willing to pay you for applying recent technologies. But be careful here. If you are one those early employees you migh have chance to put down your two cents next to a technology although things are moving so fast that you could easily see you code either getting rid of in a short term or being claimed unefficient due to lack of time to reasoning around the correct usage and patterns of too young tools. If you are coming on board little bit later then you can see proud and huge code base of React missing the immutability or complete Redux - one of those things that without React is not that big deal or something else that is not even published yet but tomorrow potentially will change the way how we modern engineers approach things. Just think about your React-Flux code 6 months ago… would you write a completely different stuff today possibly with Redux? What about tomorrow Elm or some RxJS? Right now IMO generators and yield together rocks when it comes to NodeJS control flow but I might change my mind about it tomorrow if something else comes up. Business does prefer stability and predictable stuff. The code should stay in place for a while despite technology changes rapidly. That is one of the reasons why employers should hire the right engineers. It is sad but most of us (90%) can only reason around new tech in spare time or sometimes even during working day if we are enough lucky to work for a company that knows something about the 20%-80% time usage. That leaves us with some side projects and being strong advocate of code quality/test, agile and business side - customer experience and product/service driven mindset - to make/save money to our companies even through an ugly legacy code. Dear recruiters (good ones) should understand that and cut away the bullshit. No need for marketing buzz here. Do not put React-Redux and AngularJS, Backbone in to the same advert or do not put anything like that at all. Do not ask people to know everything that is recent. A framework can be picked up in 3-4 weeks but someone who really does a quality job both on coding and consulting side is hard to find. Do not scare them with bullshit. Put some expectations on someone to be a good fit and positive personality who knows about unit testing, code management, common challenges and may be ES6 advantages when destructuring an object/array is important.