ghammell'sBlog

Welcome to my cheat sheet! I'm going to edit this document as I progress through dev bootcamp, documenting those concepts that I find are essential to know.

Ruby BASICS

Material coming soon!

Ruby Enumerables

The ruby enumberable methods are used to iterate through each component of an object:

• each object of an array
• each key-value pair of a hash
• each key of a hash
• each value of a hash
• each number in a range

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• #each
  - performs a specific block of code for each object in an array, or for each key-value pair in a hash
  nums = [1,2,3,4,5]
  nums.each {|num| puts num*2}
  2
  4
  6
  8
  10
  


• #reverse_each
  - the same as #each, except that iterates through each object backwards
  nums = [1,2,3,4,5]
  nums.reverse_each {|num| puts num*2}
  10
  8
  6
  4
  2
  


• #map
  - creates a new array, replacing each value of the current array with the output of the code block passed at every iteration
  nums = [1,2,3,4,5]
  nums.map {|num| num*3}
  [3,6,9,12,15]


• #collect
  - same as the #map method


• #select
  - creates a new array with the values from the original array that satisfy a condition imposed by the block
  nums = [1,2,3,4,5]
  nums.select {|num| num % 2 == 0}
  [2,5]


• #inject
  - works like the #each method, except it also defines a variable whose value is set to the output of every iteration (the starting point of this variable must be defined)
  
  nums = [1,2,3,4,5]
  nums.inject(0) {|sum, num| sum += num}
  15
• #cycle
  - works like the #each method, except it doesn't stop at the last iteration. It starts from the beginning again and cycles through the code an unlimited amount of times, unless a specific cycle count is defined, or if there is a specific breaking point
  nums = [1,2,3,4,5]
  i = 0
  nums.cycle {|num| puts num; i += 1; break if i == 15}
  1
  2
  3
  4
  5
  1
  2
  3
  4
  5
  1
  2
  3
  4
  5
  
  nums = [1,2,3,4,5]
  nums.cycle(3) {|num| puts num}
  1
  2
  3
  4
  5
  1
  2
  3
  4
  5
  1
  2
  3
  4
  5
  
• #include?
  - returns true or false if the array it is called on includes a specific value
  
  nums = [1,2,3,4,5]
  nums.include?(3)
  nums.include?(6)
  true
  false
  

Ruby Hashes, Arrays, Strings, Integers

Material coming soon!

JavaScript Objects

Material coming soon!

JavaScript prototypes

Material coming soon!

Looping in Ruby and Javascript (comparisons)

Material coming soon!

HTML

Material coming soon!

CSS

Material coming soon!

GIT

Material coming soon!

SQL

Material coming soon!