Programming Mistakes to Avoid

7 min readJan 6, 2022


As humans, we are imperfect. And these imperfections can be seen in various ways as programmers' mistakes and awareness are some of the most significant flaws to our success in the online world. Even the most prominent companies, such as Facebook and Microsoft, have had drastic mistakes that cost them millions. These mistakes can all be traced back to human error. The most extensive and most expensive programming mistake was in 1962. The mariner 1 spacecraft was on schedule to make a fly-by to Venus. A coding error in the rocket's software caused the spacecraft course to be severely altered. Because of this, the rocket couldn't fully launch into orbit and self-destructed. After reviewing the issue, it was determined that an extra hyphen in the rocket's coding ultimately caused the 18-million-dollar rocket to go to waste. Another Costly mistake due to human error in coding was the Morris worm. In 1988 a Cornell student developed a harmless program that ended up spreading and crashing thousands of computers. The student who created the worm was fined 10,000 dollars; however, the extensive damage was thought to have been over 100 million dollars. These two examples are drastic mistakes that have caused significant loss; however, as amateur developers, we also tend to make these mistakes.


The most common mistake among developers is keeping a consistent code line. For your code to work in a language like Python, it's essential that your lines of code can correspond and stay consistent. If you keep your coding clean and consistent, it can be easy to maintain. One way to avoid this mistake is by always keeping track of your code and ensuring it corresponds with its counterparts and looks clean and smooth. Another typical mistake developers often make in Python is having incorrect indentation. In Python, for your code to work, you have to have your line of code correspond with the following line. Unlike other languages, pythons indicate more than organization. Several blocks or code-only sequences because of indentation. One tip to help programmers with this issue is to use certain editors that show where you have indentation editors, such as PyCharm. One more mistake that python programmers tend to make is error handling. Mistakes in Python often are known as a traceback. These can be mental errors such as forgetting to close parenthesis or indent your following line of code. These are syntax errors in which Python cannot read your code due to these errors. The primary way to stop this is by mainly being very tedious about your code and always tracing your issues. Though these are all coding errors, they are all specific, and all coding languages can have errors.


For HTML, the primary error web developers often make is not adding attributes to specific tags. One example is not counting the alt attribute to the img tag. Without this tag, people with screen readers may not know what the image looks like. This can be fixed by always adding the alt attribute to your img. Another issue most encounter with HTML is not using semantics in their programming. Semantics are important ways to style your code. These are very basic and original and avoid cutting corners. These can include using measurements for your text size rather than pixels. This issue can be fixed by always remembering to use semantics instead of cutting corners. Most HTML programmers often encounter one more issue using inline styling in their code. Most experienced programmers know that using a CSS stylesheet is better for styling your HTML than using inline styling, which can give issues to your HTML document. Using a stylesheet is also semantic HTML, which applies to the 2nd issue. A way to combat this is by creating a separate styling sheet in CSS every time you make a primary HTML document. Although these issues only occur in HTML and Python, one more programming language that problems can occur is CSS which corresponds with HTML issues. An example of a subject most developers make in CSS is using color names rather than hexadecimal. Different browsers have different versions of their colors, so when you use a color such as red rather than its hexadecimal counterpart, your website's red would look different in each browser it opens. To avoid this issue, developers should start using hexadecimal and build a habit of using hexadecimal rather than using the actual color in their code.


Java is one of the biggest and most popular programming languages globally; it is utilized as an object-oriented programming language designed to have as few implementation dependencies as possible. One mistake that programmers consistently make in Java is using null references when they are not needed or utilized. When used often, Null is considered bad programming practice as it can slow your program; however, avoiding excessive Null is considered good practice. Another mistake java programmers make is not realizing that Java is a case-sensitive language meaning that uppercase and lowercase letters have different functions. Most java keywords are in lowercase, similar to other languages; however, you cannot change the case of these letters to uppercase, or else that removes the function. A way to avoid this is by being very cautious when programming in Java and realizing that you are coding in Java and not anything else. Most programmers make a more severe mistake when programming in Java in a switch statement. You mustn't break out of that switch statement. The result of breaking out of a switch statement is getting fall through. Another simple mistake programmers make is not using double-equal signs. When comparing values, it is essential to use a double-equal sign. A significant mistake that programmers also make is involved with arrays. Arrays in Java are declared and have a certain amount of components that differ from those declared. For example, if I have a variety with ten components, the index would be nine because the array hasn't declared 10. To avoid this when declaring a value, always make sure that the number declared is one value above the number of components desired. One last large mistake programmers make is missing closing curly braces. Curly braces are meant to be opened and closed; however, it becomes an error in your code when left unlocked. One way to fix this issue is by building a habit of opening and closing lines of code and keeping a mental note of whether a string is opened or closed. This major mistake can be seen throughout all programming languages and is common even among the most experienced developers.

Java Script

Javascript is defined as dynamic typing, prototype-based object orientation, and first-class functions. Though this language is the world's most popular programming language, it still has its fair share of avoidable mistakes. Developers confuse the (==) symbol and the (===) symbol. The (==) symbol's purpose is to be a comparison operator; however, the same can be said for the (===) symbol. Though these symbols have the same meaning, they have different outcomes when utilized. (==) provides a loose comparison while (===) produces a strict comparison. Only values are compared with (==), while (===), values, and datatype are compared. When these two get mixed up by programmers, it produces different value outcomes that can alter your program. Another mistake developers often make in JavaScript is not using default values. Not setting default values in dynamic variables can cause unexpected errors that are hard to trace; however, setting your default values can be considered good practice. One more mistake developers make is confusing addition and concatenation. The addition in JS can be used for regular addition between numbers and concatenation, which Is used in strings. To avoid this, as a developer, you must recognize each situation where both symbols would be used and use them appropriately.

Good Practice Habits

Practice habits in code mean adopting habits in programming that can improve the way your code runs and what it produces. Having good practicing habits means testing and implementing new and improved practices that otherwise would seem to be a hassle. Implementing these habits will set you up as a programmer for many years to come and will aid you in your journey to becoming a developer.


Digital Professionals, as a whole, are an essential part of our human society. Coding is the basis for all software on earth and is still imperfect. As developers, we are meant to find these issues and solve them, which is what is taught to us when learning to become developers. Unfortunately, these issues can still be found among the most prominent websites and companies and can destroy a company's value. Though developers create these mistakes, it is our job to solve them. Avoiding errors is one task. However, solving them is another—way to determine what mistakes you have made. Keeping comments on your code is an excellent way to start. Recognizing minor syntax errors and good practicing habits can save you the hassle of tracing back your mistakes. One central theme among code mistakes is not being tedious with your code work. Going the extra stretch and fixing minor errors before moving on to the next step was a corresponding solution to the abovementioned mistakes. Another recurring theme has lousy practice habits. Building a habit Is what can. Make your coding a lot easier, and adjusting to the new routine can set you up for successful coding.




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