• Scripting language
• Just-in-time (JIT) compiled
• Dynamic typing
• Prototype-based object-orientation
  • Prototypical inheritance
• First class functions
• Single-threaded
• Conforms to ECMAScript standard
• Multiparadigm
  • Event driven
  • Functional
  • Imperative

Typescript

• Syntaktisk “superset” av JavaScript
• “Transkompilerer” til JavaScript
• Two ways of assigning type
  • Explicit declaration let letter: string
  • Implicit type inference const num = 5

Objects and interfaces

• Interfaces describe objects

How does the event loop function?

Three main components of the event loop

• Stack
• Heap
• Queue

Stack

Function calls form a stack of frames

function foo(b) {
  const a = 10;
  return a + b + 11;
}

function bar(x) {
  const y = 3;
  return foo(x * y);
}

const baz = bar(7); // assigns 42 to baz

Order of operations:

Heap

Objects are allocated in a heap which is just a name to denote a large (mostly unstructured) region of memory.

Queue

A message queue with a list of messages to be processed. Each message has an associated function that gets called to handle the message.

Event loop

While the stack is empty, the next message is processed and the associated function is pushed onto the stack.