The first major version of TypeScript was basically "C# in JS clothing". It made the migration from C# SUPER easy for many that were used to the C# way of doing

The first major version of TypeScript was basically "C# in JS clothing". It made the migration from C# SUPER easy for many that were used to the C# way of doing things. Then throw in that many C# devs already had to know some JS for doing web applications in .Net, and you have both the motivation and the stepping stones in place to make it an easy transition.