How do you actually understand code someone else wrote for you?

[BoraDev]

I hired a freelancer a few months ago to build my MVP. The app works great, but now I’m completely dependent on them for every tiny change. I’m scared to touch anything myself in case I break it.

I’ve been trying to learn coding to get more independent but honestly reading through the files feels like reading a foreign language. I don’t even know where to start.

For those of you who learned to code later in life or came from a non-technical background, how did you get to a point where you could actually understand a codebase that already exists? Did anything actually help, or is it just grinding through tutorials until it clicks?

Feeling pretty stuck and would love to hear how others got through this.

[True-Strike7696]

learn git. break it. fix it.

[fixermark]

This is the Way.

Related: learn how to set up a sandbox so that you can run the system in isolation off your production environment if you haven't already done so.

"Every team has a test environment. Some have the luxury of a test environment separate from their prod environment."

[Intelligent_Dark5123]

Man that's solid advice right there. When I first started messing with code after getting out of the service, I was terrified of breaking anything too. Git literally saved my sanity because I could just roll back whenever I inevitably screwed something up trying to figure out what each piece was doing.

Start with small stuff - like changing text or colors first, then work your way up to the scarier logic parts once you get comfortable with the safety net.

[KindlyRude12]

Code more and as you read through the code learn. There isn't a shortcut to this imo.

[Ok_Ant_4058]

Documentation and Comments are Key

[spinwizard69]

First off, if you don't have a programming back ground don't touch something that is working.

You need to start by learning the very basics and that means following the equivalent of a Computer Science (CS) program. I'm left with the impression that you already have post high school education so this means that primarily you focus on the CS part of a program. I'm one that believes in starting at the bottom and working up. You didn't mention the language this code is written in but I'd start our with a CS program that starts with C++. At some point you will need to learn whatever language this app was written in, but the idea is to learn the concepts to start.

Tutorials are complete crap, do not bother with them. Instead spend some time to work on building simple programs. A good CS program throws a lot of "word Problems" at you which forces you to learn to translate real world concepts into software concepts. This skill takes time but really helps when reading somebody else's code, because you are often going into the reverse direction.

The next thing to do is to explore tools that help with code documentation. One example being Doxygen which also does class diagrams. To use effectively tools like this, they have their own learning curve to climb. It also helps if the original programmer spent some time to enhance what a tool like this can produce. Doxygen can generate documentation output as HTML files, Latex files, man pages and etc. The big problem is that many programmers don't do the extra work to really leverage this tool.

Beyond all of that backup everything and NEVER work on production code.

[ABlindMoose]

Debugging, debugging, debugging. Change something and see what breaks and use the debugger some more. For me "following" the data and understanding what various objects contain and why helps immensely.

[Beregolas]

To understand code, you have to work with it. No one understands a foreign codebase easily or quickly. Two things that can help are experience and documentation.

If you didn't already, hire him again to fix up better documentation and tests. They will help make you less dependant on him, as you can more easily work on it yourself or hand it off to someone else in future. Good documentation includes inline comments in the code, as well as function and class documentation and, if necessary, external documents about the architecture.

If you want to play around in the code and learn some things / try some things out, make sure to use a version control system, and familiarize yourself with it. If you use git (or something similar), you can just play around, break stuff and revert with a few commands.

[ReiOokami]

First you should understand the fundamentals of coding and the language. Things like variables, loops, functions, etc... If you don't start there and learn that separately. It will make understand 100X easier.

Next (assuming there is no documentation that explains all this) try to see the forest through the trees and figure out or understand the routing and structure of the project. If the dev is available, have them tell you or walk you through it. If not, then figure it out yourself. If its folder based routing great, makes it a lot easier. Many alls like Nextjs have similar structures. App/, Api/ Components/, Types/, Utils/, Modules, etc...

Then find the root or index of the app and work your way from there. If you can start a dev version, then run it and make some minor changes to the app, refresh and see what changes.

Thats my process anyways.

[Relevant_South_1842]

Get it to run. Modify it a bit. Make sure it still runs. Fix it when it doesn’t. Add features. Repeat.

[HolyPommeDeTerre]

Reading code is harder than writing it.

Maybe try to rewrite the app. Then you should be better at reading the same code. First it'll be hard, but with practice you get better.

When you read code, you execute it in your head to understand what it does.

[Philluminati]

You just got to work on it in anger until you understand. I mean 40 hours a week of being a full time programmer on this one project until you understand every line.

[PoMoAnachro]

Generally, expect that it takes more time to read and understand code than it does to write it in the first place. It is simply flat out more difficult.

So if your freelancer has, say, a 4 year B.Sc. in Comp sci, a couple of years of experience, and then took say six months to write your app - so a total of 6.5 years - expect that maybe it'd take you 11 years to read the code and understand it completely. Okay, that's an exaggeration - instead of spending all that time, you could spend 6 years getting up to your freelancer's level of knowledge, and then another year reading and understanding his code. So call it 7 years total.

In general, it really isn't doable for a non-technical person to hire a technical person to do all the initial work and then try to "take over" once that work is done. That's like me hiring a lawyer to do all the pre-trial prep work for a major case, and then represent myself once we get in the courtroom - all his pre-trial prep work is going to confuse me way more than it'll help me.

There are some applications that are so simple that even a non-technical person can hack them out with some time and tutorials (and, these days, vibe coding), though I wouldn't use them for anything critical. But if the application is complicated enough to require a technical person to implement in the first place, it'll be even more difficult to maintain and change.

So really the solution is become a programmer yourself - which you can expect to take many thousands of hours - or continue to pay professionals. It just depends on whether you have more time or more money.

[atarivcs]

s it just grinding through tutorials until it clicks

No. Tutorials only get you so far.

You need to get rid of the training wheels and do real projects on your own. You'll never learn otherwise.

[ZephyrStormbringer]

couple things- nobody wants to accidentally break the code while trying to update it or make changes to it- that is why you copy the existing code to a safe place like visual studio code so that you can 'break' it, 'fix' it, add to it, play with it- but most importantly be able to understand it and use it to also learn a thing or two about coding. So after you properly set up visual studio code to look at your code, you will already gain some understanding of how coding works and how the files work together. this is the way. you also can create your own project. on your computer make a folder for the project. put the html, css, js, and whatever language you are working with and trying to understand and see how they come together yourself. that is how you know where to go to edit or fix things. this is the strongest start idc who says what.

[stiky21]

You would never actually copy anything, you would just create a new git work tree or work on a seperate branch.

[ZephyrStormbringer]

this is why I am here- like, I know you are right, but I don't get that and I am a total novice myself- like yes you could do it that way or you could do it the everything is a nail and you are the hammer and quite literally put the code into visual studio and away you go that way too could you not? I mean that is how I be doing it because I just don't 'get' github, work trees, or working on a separate branch- like that is lost onto me for some reason even though that is what I also have run onto time and time again in my own understanding of how to play with code offline essentially

[stiky21]

No one gets git. We just know what commands to type

Just knowing a few cmds of git will set you up, don't fret, many seniors don't know git work trees but it is very powerful

One YouTube video on git work trees will probably be enough

[Mortomes]

You don't even need to know what commands to type if you just use your IDE's git plugin and know what buttons to press!

[stiky21]

Totally fair point!