Javascript is...

• Not Java nor Java-like
• A single-threaded, asynchronous (non-blocking), dynamically-typed, and weakly-typed language
• An imperative language (primitive language) with some functional-like aspects and OOPS feature (enhanced in ES6)
• An interpreted language

history of javascript

• Created by Brendan Eich at Netscape for its browser, Navigator
• JavaScript history names: Mocha -> LiveScript -> JavaScript -> ECMAScript
• In today's world, ECMAScript is a standard whereas JavaScript is an implementation (will talk more about ECMAScript later)

single-threaded

• There is one and only one thread called main thread handling tasks (what is a thread? think of it as worker in a factory)
• JavaScript has been traditionally known as a single-threaded language, but modern JavaScript is no longer single-threaded thanks to web worker and service worker.

Async & non-blocking

• In the browser environment, what things are blocking?
• What could happen if code is blocking the browser?
• Async is the savior

Dynamic typing & weak typing

• Dynamic typing:
  • Type is determined at runtime
  • No need to specify type for a variable at declaration
• Weak typing:
  • Type can be magically converted to another type at runtime

Imperative language

• A.k.a. primitive language
• JavaScript can also be functional and OOPS

Interpreted language

• Code is interpreted at runtime, meaning that a runtime engine (like Chrome v8) needs to parse and compile your source code before it can execute it
• Not performant compared to compiled language such as Go