During a few months of working at the High School for Graphic Design and Sustainable Construction in Split, I noticed that some of my students take a lot of concepts and scientific knowledge for granted, and that they do not have the necessary understanding of certain terms. Motivated by such a situation, I decided to conduct research on the topic of " misconceptions related to the basic concepts of the “javaScript” programming language. They use certain concepts in the programming of simple tasks in order to come up with a solution to the task that works, without understanding and having a deeper understanding of what actually happens in the background, how and in what way the tasks are compiled/interpreted, and I believe that these are important concepts that cannot be just to bypass or skip it, because after all, the school where I taught is a vocational school, after which the students are ready for the labor market. Misconceptions are wrong mental ideas that students create during the acquisition of new knowledge, i.e. misinterpretation of certain concepts and the inability to understand certain concepts or a set of, in some way, related concepts that are often influenced by prior knowledge acquired in areas such as mathematics [1]. When a misconception is actively built, it is not easy to replace it with a correct concept because students put effort into creating them and also prefer simpler solutions. Wrong answers are desirable for professors because they can serve as an extremely useful tool for creating new knowledge that is in line with scientific facts and knowledge. For this reason, it is very important that teachers are able to recognize certain misconceptions, react to them correctly, and with the help of them, help students build concepts that are appropriate. This especially applies to those areas that are inherently complex, and programming is certainly one of them. The goal of this research is to determine misconceptions related to data types using “JavaScript” as a programming language.