Ruby vs Javascript vs Python : Syntax & Semantics

An analogy between the Ruby, Javascript, and Python languages

Table Of Contents

1. Basics Intro
2. Arrays Functions
3. Compound Arrays
4. String Functions
5. Numerical Functions
6. Logical Conditions
7. Class and Methods or Functions
8. Regular expression (Regex)
9. Type Conversion
10. Heredocs

Basics Intro

Description	Ruby	Javascript	Python
Start Cli	irb	python	node
Integers & floats declaration	x = 1 ; y = 0.23	let x = 1; var y = 0.23	x = 1 ; y = 0.23
Contants Declaration	W = 'ruby'.freeze	const w = 'js'	W = 'ruby'
Variables in strings	"one is #{x}"	one is ${w}\	"one is {}".format(x)
Line Comment	# this is comment	// this is comment	# this is comment
Block comments	=being ; =end	/* block comment */	''' block comment '''
write output	puts 'write output'	console.log('write output')document.write("write HTML")	print('write output')
Arrays , Lists	arr = [1,'a',true] ; arr = Array.new	let arr = [1,'a',true]	arr = [1,'a',True]
Hashes, Objects, dictionaries	hash = { 'a' => 2, :b => 4 }	var obj = { 1 : 2 , 'a' : 4}	dict = {1: 2, 'd': 'e' }
Destructuring	a,b,c = [2,3,4] ; p b	var {x : a , y: b} = {x : 1, y : 2} ; console.log(b)	a,b,c = [2,3,4]

Arrays Functions

where x is [3,4,5,6,7,8]

Description	Ruby	Javascript	Python
Remove last element	x.pop x.pop(2)	x.pop()	x.pop()
Remove first element	x.shift(9)	x.shift()	x.remove(x[0]) del x[0]
Add last element	x.push(9) x.append(9) x << 9	x.push(9) y.concat(5)	x.append(9); x.extend([9]); x.insert(len(x), 9)
Add first element	x.unshift(2)	x.unshift(2)	x.insert(0,2)
Sort	x.sort	x.sort()	x.sort()
Reverse	x.reverse	x.reverse()	x.reverse()
Count	x.count(6)	var count = {}; y.forEach(val => count[val] = (count[val] \	\
Length	x.length; x.size; x.count	y.length	len(y)
Maximum	x.max	Math.max(...x)	max(x)
Minimum	x.min	Math.min(...x)	min(x)
index	x.index(3)	x.indexOf(3)	x.index(3)
insert	x.insert(2, 'Feb')	x.splice(1, 0, 'Feb')	x.insert(2, 'Feb')
Make a copy	y = x.dup	let y = [...x]	y = x[:]
Select, filter	x.select{\	el\	el > 4 }
Reduce	x.reduce(:+)	lx.reduce((result,el)=> result + el,0)	reduce(lambda result,y: result + y, x)
Map	x.map{\	el\	el*2}
Each	z = [] x.each{\	el\	z << el*2} p z
Reverse loop	z = [] x.reverse_each{\	el\	z << el*2} p z
Clear , Reset	x.clear	x = []	del x[:]

Compound arrays

where, x is [1,2,3] & y is [2,4,5,6]

Description	Ruby	Javascript	Python
Intersection	x & y #=> [2]	x.filter(e => y.includes(e))	list(set(x) & set(y))
Union	x \	yx.union(y)	var z = [...x,...y][...new Set( z )] 'or'Array.from(new Set(z))
Join	x + y	[...x,...y]	x + y
Difference	x - y	x.filter(e => !y.includes(e));	list(set(x) - set(y))

Strings Functions

where, s = 'Cheat sheet '

Description	Ruby	Javascript	Python
UpperCase	s.upcase	s.toUpperCase()	s.upper()
LowerCase	s.downcase	s.toLowerCase()	s.upper()
SwapCase	s.swapcase	NA	s.swapcase()
Trim	s.strip!	s.trim()	s.strip()
StartsWith	s.start_with?('cheat')	s.startsWith('Cheat')	s.startswith('Cheat')
Repeat	'Hi ' * 3	'Hi '.repeat(3)	'Hi ' * 3
Split	'asdf'.split('')	'asdf'.split('')	list('asdf') 'a#s#d'.split('#')
Join	['a','s','d','f'].join()	["a", "s", "d", "f"].join('')	''.join(['a','s','d'])
Replace	s.replace('Hey')
Find
Count

Numerical Functions

where, el = -22.45

Description	Ruby	Javascript	Python
Ceil	el.ceil	Math.ceil(el)	import math math.ceil(el)
Floor	el.floor	Math.floor(el)	math.floor(el)
Round	el.round(1)	Math.round(el)	round(el)
Absolute	el.abs	Math.abs(el)	abs(el)
Random	rand(10)	Math.ceil(Math.random(10) * 11)	import random random.randrange(1,10)
Zero	el.zero?
Negative	el.negative?

Logical Conditions

Description	Ruby	Javascript	Python
If	if elsif else end	if : elif : else:	if () {} else if () {} else {}
case	case a when else end	switch(expression) {case x:break;case y: break; default:}	NA
Ternary Operator	true == false ? 1 : 2	true == false ? 1 : 2	1 if (True == False) else 2

Class and Methods or Functions

Description	Ruby	Javascript	Python
Instance Methods	def name(input) p inputend	name = function(input) {return ${input};} name = (input) => "input"	def name(input): print("This is " + input)
Static Methods	def self.age(input) p inputend	static age(input) {return ${input};}	@classmethod def age(input): print("This is " + input)
Class	class Personattr_accessor :name def initialize(name)@name = nameendend	class Person {constructor(name) {this.name = name;}}	class Person:def init(self, name):self.name = name
create instance Object	p = Person.new('Bezos')	let p = new Person("Bezos")let p1 = Object.create(Person)	p = Person("Bezos")
Single Inheritance	class Employee < Persondef initialize(name)super name@name = nameendend	class Employee extends Person {constructor(name) { super(name)this.name = name;}}	class Employee(Person):def init(self, name):self.name = name
Multiple Inheritance	module Studentdef walkendend class Personinclude Humanend	class Student extends Person	class Student(Person):
default values	def name(input='bezos') end	function(input='bezos')	def name(input='bezos')

Regular expression (Regex)

where, lx = "titan titan titan"

Description	Ruby	Javascript	Python
First occurrence	lx.match(/t[a-z]*n/)[0]	(/t[a-z]*n/).test(lx) //=> true	import rere.search("t[a-z]*n", lx).group()
All occurrences	lx.scan(/t[a-z]*n/)	lx.match(/t[a-z]*n/gi)	re.findall("t[a-z]*n",lx)

Type Conversion

Description	Ruby	Javascript	Python
string to Integer where, str2int = \'99\'	str2int.to_i	int(str2int)	parseInt(str2int) Number(str2int)
Integer to string where, int2str = 66	int2str.to_s	str(int2str)	int2str.toString()

Heredocs

Description	Ruby	Javascript	Python
Multiline string	content = <<~HEREDOCI welcome your contributions.please suggesta topic or report an issueHEREDOCp content		content = """ I welcome your contributions.please suggesta topic or report an issue"""print(content)