I Have Helped Hundreds Of Self-Taught Programmers With The Right Resources. I Had Talked To Them When They Were Unmotivated And Wanted To Quit Their Jobs. 

I learned how to code them. What kind of mistakes do they make early in their career? Which problems do they have the most issues solving?

After talking to hundreds of self-taught programmers, I can now tell if a self-taught programmer is experienced or not.

1. They try to choose similar technology sets.

Most self-taught people tend to choose the same set of technologies. They are not ready to step out of their comfort zone and don’t want to learn anything new.
If management asks them to learn a new language, they try to convince their manager and team why the language they already know is better for the project. If they are asked to learn the React
framework but are comfortable with Angular, they will try to participate in projects using it. They are not ready to deal with unfavorable situations. As a developer, you’ll never grow in the industry if you can’t get out of your comfort zone.

2. They have a “we’ll do it anyway” attitude.  

Its self-taught programmers don’t care about code quality and don’t focus on their coding style. They want to create the desired feature in the software. If they can make what the company wants, they feel productive.
If they do not complete their tasks within the specified time frame, they feel that their efforts have been in vain and that all their work days have been wasted.
They don’t understand that sometimes programmers need more time to write quality code; in these cases, they are coding until the last minute of the deadline.
If the programmers wrote code that was not easy to read and maintain, they could finish the project before the deadline. Code quality is essential.
Programmers sometimes need more time to complete a project to ensure the code is readable. This does not mean that the hours spent creating high-quality code are wasted.

3. They write repetitive code.

No developer wants to maintain a poorly written project. It becomes challenging to manage if a codebase has code posted thousands of times.
Self-taught developers repeat a lot of code. They believe that if the software works correctly, there is no need to remove duplicate code.
They forget that copying and pasting the same code is bloating the codebase and telling you that all this extra code will only take a few seconds to run.
But a web application, with a delay of one millisecond, will bring heavy losses to the employer. With each unnecessary line of code, the client needs more space on the server.
A good code base that is well-written and with little repetition ensures that the program runs faster and takes up less space.

4. They do not perform any unit tests.

Self-taught programmers assume that their code will not be broken by any software testing method. They check their code only by calling the code together with manual tests.
They easily interact with any web application they create. If it works well, they act like everything is fine, and there is no need for automated testing.
After talking to developers, I can tell you to use a test-driven development approach as much as possible. This is the only way you can then trust your code.
Even if you forget to manually test after making changes to the code, this test-driven development ensures the high quality of your code. It is also considered a document that always exists next to the code.

5. They are looking for the most attractive technology.

This is the funniest one. If I see a self-taught programmer looking for the fanciest technology, I consider him inexperienced. You can call me a bit biased.
I’ve noticed that inexperienced programmers usually discuss the next big thing, and everyone wants to work with the latest technology.
When a less experienced developer sees someone working with an almost older programming language like PHP, they look down on that developer.
They believe that a developer is wasting his life if he is not working with the latest language and computer environment.
These self-taught, inexperienced programmers often have taken video tutorials on the latest technology. After watching the video, they consider themselves an expert in that field.
But to become an expert, you need to create a real-world project, Not that you have just completed a training course.

In summary:

1. They try to choose similar technology sets.
2. They have a “we’ll do it anyway” attitude.
3. They write repetitive code.
4. They trust their code too much.
5. They are looking for the most attractive technology.