12 Senior Developer Traits Junior Developers Need To Master

The fastest way to get to the top in any field, whether it is arts, sports or software development is to study the people that are already at the top… 

And do what they are doing that you are not.

If you write code for a living, this means taking a look at Senior Developers. It means identifying what skills, habits and traits they possess that you don’t. 

After spending thousands of hours in the last 3 years working with top notch Software Engineers worldwide, I found out that there are 12 Senior Developer traits that you can put in place right now to fast-track your growth to the next level. 

Let’s start with number one…

1. Focus

Focus means saying no to some things, so we can do others. 

Ideally, saying no to the things that don’t matter. And saying yes to the stuff that makes a difference. The stuff that moves the boat faster. 

This is really hard for many developers because it goes against our natural instinct. It means accepting that you can’t do everything. And that not every opportunity is created equal.

You can’t learn every new framework out there. You can’t read every newsletter. You can’t attend every conference. And you don’t have to.

Your time is limited. So is your energy. 

Being a Senior Developer means picking your battles. 

Funny enough, the better you can pick, the faster you will progress. Senior Developers have the same 24 hours in the day that you have. But they get more done.

How?

By doing less.

When a new thing comes your way, ask yourself "Does this really matter?" Or is it just another trend? Chances are it is just another distraction disguised as an opportunity. 

Senior Developers say more no’s than yeses. They finish more projects than they start. And they master the framework they already work with, before learning a new one. 

If you want to get to Senior faster, the first trait you need to develop is focus. 

2. Second Order Thinking

One thing that screams “Junior dev” is the attitude of “let’s build it and we will find out”. Juniors have a bias for coding first and thinking second. 

That can be a good attitude if you are just starting out, but when you are working on production ready software, some technical decisions you won’t be able to change. Or change easily. 

For example, you choose Vue as a frontend framework.

Then, requirements change. You start thinking React would be a better option. Sure, you can switch to React. But it will be neither easy nor cheap.

Senior Developers know it is easy to get high on your own supply. But if you fall in love with the frameworks and libraries you know best, you will start making poor technical decisions.

They think twice about the consequences of their choices. This can mean asking the “five whys” when trying to understand a problem.

Or thinking about the possible drawbacks their solution could have.

For example, now that we have added Redux, global state might be a bit easier to manage. But we will have to onboard new developers on Redux. The learning curve is high.

And our JavaScript bundle will get bigger which is not good for performance.

Considering second order circumstances will make you a much better developer. It will also help you during technical interviews.

🚨 P.S. Are you looking to fast-track to Senior Developer with quality resources, feedback, and accountability? Click here to join our Free Community - The Senior Dev Academy. 🚨

3. Pragmatism

When Junior Developers read a book on best practices, they jump and try to apply them to every line of code in any release. They follow them religiously. 

If you can't make technical decisions by yourself, it is much easier to stick to predefined rules. But software development is not a religion.

A good example is Testing.

When a Junior dev reads about TDD (Test Driven Development), they will start trying to test everything. Aiming for full test coverage. When in fact, complete code coverage gives diminishing results and will turn out to be a waste of time.

Senior Devs know how to balance best practices and time to market. When to take shortcuts and when not to. 

Hacking things quickly will generate bugs and technical debt. Always sticking by the rules when the context of your code changes will result in bad decisions.

You need a balance. 

Be open to reconsidering your technical choices based on circumstances.

4. Nothing To Prove

Because of lack of confidence, Junior devs find themselves constantly trying to prove themselves to others. Same with Senior developers who are insecure about their value and skills. 

They base their confidence on the validation they receive from others.

This is a losing game.

They will try to show how much they know in a certain technical discussion, talking over others, or pushing code late at night or over the weekend.

In reality, all these behaviours create a toxic team environment and backfire. In the best case, they will make you look less Senior than you actually are. 

There are two ways to deal with this. 

The first one is to stop spending so much on external validation. Because the truth is you don’t need to prove yourself to anyone. Only to yourself.

The second is making peace with the negative voices in your head.

You can be your worst critic. Perfectionism, fear of failure and a mistaken idea of what a “real” developer is are destroying your self-esteem. That’s why no matter how hard you work you always feel like falling short. 

It’s time to get out of your head.

Focus on mastering your craft and the rest will follow. 

You will instantly become more confident in yourself and your skills. And you will stop trying to prove yourself to strangers.

5. Master The Fundamentals

Whenever I bump into a LinkedIn profile of a developer and they describe themselves as a “React” developer, or an "Angular"' developer, I know they are not Senior. They might be Senior in that framework, but not Senior overall.

A Framework developer will never be a Senior Developer.

Frameworks don’t make you Senior because frameworks are only the icing on the cake. Not the cake itself. The tip of the iceberg, versus its bottom.

I would even speculate that behind the current epidemic of Impostor Syndrome among software developers, even Senior ones, is not  lack of talent or lack of hard work. 

It is weak fundamentals.

This is also why topics like debugging or performance optimisation are a guessing game for most developers. They are not used to digging below the surface of the libraries and tools they are working with.

To become a Senior Developer you must not only understand the “What” but also the “Why” behind things.

A Senior developer would, for example, not only be able to build a React application. But they would also understand why React has been built in a certain way. And how it blends together with the language it’s been written in (JavaScript/TypeScript) and the platform it runs on (the Web Browser).

The good news is that once you get the fundamentals handled, the level of everything will rise.

🚨 P.S. Are you looking to fast-track to Senior Developer with quality resources, feedback, and accountability? Click here to join our Free Community - The Senior Dev Academy. 🚨

6. Deliver End-to-end 

The #1 reason why companies avoid Junior developers is that they need a lot of external help to get things done. External help means you will be bothering a Senior developer to get your stuff done. 

Junior developers are considered “expensive” because they can’t deliver independently.

Instead, Senior developers can deliver end-to-end. Give them a bunch of requirements and they will figure out the rest. This doesn’t mean they are lone wolves, they are usually great at working in a team. 

It doesn't mean Senior devs hack things quickly just to push them forward.

That’s not a “real” Senior.

And it doesn’t mean that they know every part of the software development lifecycle in depth. 

But, Senior developers understand all the major pieces across the software development life cycle. And can contribute to each of them (frontend, backend, deployment).

If you are a Junior/Mid developer looking to level up, end-to-end delivery is one trait you need to put your eyes on.

7. Mental Models 

One of the main things that sets Senior devs apart from more Junior ones is the amount of complexity they can handle.

Seniors can understand more complex codebases and requirements. 

They can understand second-order circumstances. How changes in the codebase will affect performance, costs, and even the team. 

And they do that not because they memorise every implementation detail. That's impossible because human memory is very limited.

They do that because they abstract the complexity of the code into mental models. These are simple ways of representing reality.

How can developers build quality Mental Models?

By looking behind frameworks and libraries and learning the design patterns behind them. There is a lot of noise out there depending on your tech stack. Things like SOLID principles, or MVC…

But I think the best way to start is by picking whatever framework you are working with and trying to look beyond the code.

Start asking yourself, why did the creators of the framework build it this way? Is it built on new concepts or is just an implementation of age old principles (which is usually the case). 

By answering these questions you will build your own mental models on software development, and be able to handle more complexity. That’s one of the most effective ways to fast-track your growth to Senior Developer.  

8. Senior Developers Control The Story

One thing Senior Developers can do extremely well is leading technical discussions and influencing other people around them. Be it business stakeholders, product managers or fellow developers, Senior devs know how to guide them in the right direction.

They do this using a mix of assertiveness, technical expertise and communication skills. 

Senior developers are also able to set strong boundaries. 

They can disagree without getting emotional. They can stand up for themselves (and others) during meetings. They negotiate their salary aggressively. 

And they tell their own story.

If another developer starts blaming others during a code review, Seniors know how to stop them. If higher management tries to get in a developer’s work and micromanage, Seniors know how to push them back without damaging the relationship. 

There is no step-by-step guide on how to become more assertive as a developer. 

It takes repetition and practice. The first step is to stop saying “Yes” all the time. And to start trying to get your way in salary negotiations. 

🚨 P.S. Are you looking to fast-track to Senior Developer with quality resources, feedback, and accountability? Click here to join our Free Community - The Senior Dev Academy. 🚨

9. Long Term Thinking

Junior developers think for “now”. They think short term. That is true for their code, when they take shortcuts. A Junior Developer will extend a piece of code without thinking about refactoring it properly or simply ignore testing and performance.

But Juniors also think short term about their careers. 

This can mean job hopping too much or burning bridges. It can mean neglect. 

Like not improving your skills or the way you sell yourself because right now your job is stable. Just to regret it six months later after getting laid off.

Part of becoming a more Senior developer is starting to think long-term. 

The first way to do that is by changing your mindset. Most short-term thinking that Junior devs have is not caused by laziness but by self-doubt.

Deep inside they are still thinking whether being a developer is the right thing for them. Or whether they picked the right career.

These doubts stop them from committing long-term.

And now with AI threatening the end of software development, this short term thinking is more frequent than ever. Why commit to something anyways if it is going to be gone soon.

Trust me on this, it is only when I made a full commitment to my career as a developer that things started to take off. 

I said “this is it”. I stopped looking outside. I told myself: this is my job now and it will be my job for the next decade so let me do it well. 

I started investing in my skills because now I know they will pay off. 

Even if you are not going to write code for the next 20 years, having a long-term mindset will bring you great benefits. Senior developers got to Senior level because they committed to their craft. If you aspire to get there, you should do the same. 

10. Excellence Is A Habit

I think it was Kent Beck who said the famous phrase “I am not a great programmer, just a good programmer with great habits”. Habits are important because they stand the test of time. 

Because any kind of knowledge you have about a JavaScript framework will sooner or later become obsolete. Technology changes. But your habits will stay with you forever. 

The good news is that humans are creatures of habit.

It is not easy to set new routines in our brains.

But once we interiorise them as habits, we have an easy time following through. The best way to take advantage of this is to get whatever goal you have, break it into daily actions. Then turn those actions into habits through repetition.

For example, if you want to get better at testing, write one unit test every day. 

If you want to be more prepared in the daily meeting, and think clearly, keep a journal. If you want to find a new developer job, and you have to send 100 applications, send 10 applications every day. 

Set up new habits and your progress towards the Senior level will be constant and steady. 

11. Protect Your Most Important Asset

Being a Senior Developer means thinking long term not only about your code and technical decisions but also about your health.

Because health is wealth.

I talk about this again and again in my videos.

Developer jobs are extremely sedentary. You spend most of your day sitting in a chair in front of a computer. That is very bad for your health. 

Then, there is all the trash food, like chips, soda and candy in the office. This means unless you make a conscious effort, it will be hard for you to stay healthy and in shape.   

But if you want to have a long and productive career writing software, and you don’t want to end up with back problems, diabetes or even something worse, you need to start taking care of your health.

This doesn’t mean you have to start hitting the gym 5 times a week. 

Or go on some crazy diet. But do sports at least 2 to 3 times a week. You can hit the gym, go for a run or do a team sport. Right now I am doing 

On the diet side, cut on sugar and refined carbs. Don’t overdo it with the meat either. 

Consider your mental health as well.

Ignore advice like “eat, sleep code, repeat” and build a life outside of work.

Start a new hobby. Reach out to a friend. Take breaks. 

In the short run, you might progress a bit slower. But in the long run you will be able to stay in the game for a longer time.

12. Close The Circle

Finally, Senior Devs understand how karma works. They know that no matter how hard they work, or how smart they are, dozens of people helped them on their way to the top. 

This doesn’t take away their merit but acknowledges other people as well. 

So they close the circle. 

They help other developers out. And they do it without expectations. 

Not because it might get you a promotion. Or status, or admiration. They do it because it is the right thing to do. 

Helping someone who is just starting out will give you back part of the spark. The passion and curiosity that a beginner feels when they see things for the first time is so contagious.

Another thing you can turn into a daily habit! 

Okay, this is it. Put in place these 12 traits and you will fast-track your growth to a Senior level and beyond. 

Moving forward, here are 2 things I want you to do: 

1. What are some traits you’ve seen in Senior Developers that you think we should add to the list? Comment below, and I will try to answer all your comments! 

2. If you are an ambitious developer trying to level up and you are searching for a community of like minded people, click here join our free community for JavaScript developers looking to fast-track to Senior level.