I learned about 8 years ago and I think the first, hardest part is grasping the fundamentals - firstly data structures and algorithms. Things like visualizing the storage of data types in variables and using them later. Things like when you create a variable you create an empty box and assigning something to that variable is like putting the variable in the box. A tool to be able to visualize what an array of tuples looks like as you write code to store values would be pretty neat for instance.

I think that first hurdle is the most important by far because once I crossed that it felt like I knew I was actually capable of being a software engineer. The next difficult jumps for me were grasping OO concepts like polymorphism and inheritance and learning functional programming. I also struggled with async style programming (first callbacks, then promises) as well as understanding contextual values such as Javascript’s this.