johnantoni / javascript-parts

a side order of notes, problems and pointers to crush that interview

Anonymous Functions

• Anonymous functions are functions that are dynamically declared at runtime.
• They are declared using the function operater instead of the function declaration.

named function

function triple(x) {
  return x * 3
}

anonymous function

var triple = function(x) {
  return x * 3
}

First Class Functions

• they are stored in a variable or array
• or passed as an argument to a function
• or returned from a function

Higher Order Functions

• help with composition allowing us to place little functions into bigger functions and so on.
• reducing complexity.
• functions that operate on other functions.
• to aid in readability and maintainability.

what's the difference between let & var

• unlike let, var suffers from hoisting
• variables declared using var can be accessed in the whole scope
• we can access them before they're used

example

function parent(data) {
  var i;

  // var is declared inside here but hoisted to the top of the parent function
  // so will wind up giving undefined as it will pollute itself
  // let would work better, as it's will remain inside our for loop
  for (var i = 0; i < data.length; i++) {
    console.log(data[i])
  }
}

Prototypal Inheritance

A prototype is a working object instance. Objects inherit directly from other objects.

Classsical Inheritance

Classes inherit from classes and create subclass relationships: hierarchical class taxonomies.

• Gorilla / Banana Problem: What you wanted was a banana, but what you got was a gorilla holding the banana, and the entire jungle