TypeScript

TypeScript is a progamming language that is based on JavaScript. In fact TypeScript is written just like JavaScript with added syntax for types and compiles into JavaScript with none of its own syntax left around. The type system of TypeScript has many key features that it adds, some of these are:

• Helps to catch errors during development
• Uses 'type annotations' to analyze code
• TypeScript is only active during development. This simply means that all TypeScript code when compiled into JavaScript doesn't stick around and the machine running the JavaScript code ie: a web browser has no idea what TypeScript even is.
• TypeScript doesn't provide any performance optimization

Since TypeScript compiles to JavaScript and doesn't leave any of its own syntax behind going forward we think of TypeScript as JavaScript with annotations added. Although it isn't a requirement to know JavaScript before learning TypeScript I would highly recommend you have an understanding of at least the basics before learning TypeScript.

If you are completely new to TypeScript I would recommend viewing the following topics in order, however if you are here for information on a specific topic feel free to skip around:

• TypeScript Type System
• TypeScript Annotations