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Reading Notes Code 301: Day 10

JavaScript Call Stack

Function execution occurs in a hierarchical manner, one at a time, from the top to the bottom
Call stack uses “last in first out” principle (AKA LIFO)
The following line of code would run in order from 1-3 (firstFunction through thirdFunction):

function firstFunction(){
  throw new Error('Stack Trace Error');
}

function secondFunction(){
  firstFunction();
}

function thirdFunction(){
  secondFunction();
}

thirdFunction();

(source)

As a function is called, its parameters and variables are pushed stacked one on top of the other, in order. They pop out from the stack and memory is cleared up (see diagram below):

(source)

Think of yourself standing on a queue, in a grocery store cash point. You can only be attended to after the person in front of you have been attended to. That’s synchronous. This is what we mean by “manage function invocation”. (source)

JavaScript is synchronous in the same way!
Stack overflow is when a function calls itself but doesn’t have an exit point. It runs over and over. Example as follows:

function helloTim() {
  helloTim();
}

helloTim();

JavaScript Error Messages && Debugging

Types of error messages:
- Reference Errors
  - You tried using a variable that hasn’t been declared
- Syntax Errors
  - Just like it says, something wrong with your syntax
- Range Errors
  - Giving invalid lengths to arrays/objects
- Type Errors
  - Incompatible data type
console.log() is invaluable in debugging
Remember that you can add breakpoints during the debugging process