Learners' success in Massive Open Online Courses (MOOCs) and the factors influencing it have previously been examined mainly upon completion of the course. This approach does not reveal whether learners are fulfilling their initial intentions regarding MOOCs and which factors affect it and thus the individual success of the learners. This quantitative study using decision tree analysis with the CHAID growing method was conducted. The dependent variable was learners' success, and it was measured as a difference between learners' intentions and their actual course performance. Aspects of learners' background, engagement and motivations were used as independent variables to determine which of these affect learners' success in computer programming MOOC. Data was collected from learning platform and with voluntary questionnaire. The results showed that over two-thirds of the learners in this study were successful. Success was influenced by learners' prior education, use of the referred external materials, prior experience with programming and online courses, and only one motivational factor -- "Usefulness related to certification." Prior education had the strongest impact. The results indicate that learners' success is affected by previous learning experiences. It is suggested to complement learning materials with links to external materials and develop a range of support mechanisms for learners to choose from. This study expands previous research on learners' success, basing the measurement of success on learners' intentions. This knowledge can be useful for MOOC organisers who can re-evaluate the resources used on the courses.