Current programming practices rely heavily on the use of APIs (Application Programming Interfaces) and frameworks. However, APIs can be challenging to learn and use. Existing research focuses on specific barriers programmers encounter while learning APIs, providing a fragmented understanding of the process. In this paper, we analyze the holistic process of twelve programmers learning the React JS API using sensemaking theory as a guiding framework for qualitative coding of behaviors. We describe how these API learners moved through sensemaking stages and how they interacted with information during each sensemaking stage. Our results highlighted programmers’ tendency to seek understanding when they encountered problems.