1. Introduction
   1. What is typescript?
   2. Why do you need typescript?
   3. Why don’t you need javascript?
2. Best practices
   1. Use unknown type if you need any
   2. Don’t use optional parameters in callbacks

A programming language with type systems on top of javascript

• Easy to catch mistakes by specifying types
• Appropriate for enterprise applications
• Applying OOP(Object-Oriented Programming) concepts such as interfaces and classes in your codebase
• Makes it easier to understand your codebase
• Awesome tooling System

• Learning overhead
• Compile to execute javascript code-it adds another step in the development process

• unknown forces you to narrow down types, so you can deal with the variable case by case, while any doesn’t give you any information about its type.

• You can pass in functions with fewer arguments even if you don’t use optional parameters in callbacks
• Use it when you mean to explicitly write parameters.