CoffeeScript Tutorial 2
In this video I’ll finish the CoffeeScript tutorial I started in my previous tutorial. If you haven’t watched, watch it first.
This time I’ll cover CoffeeScript Arrays, Ranges, Splats, Filter, Reduce, For, Guards, Isnt, Is, While, Do While, Functions, Objects, Classes, Inheritance and more. All of the code like always follows the video below.
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Code From the Video
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# ---------- ARRAYS ---------- # Arrays can contain multiple data types randArray = ["word", false, 1234, 1.234] csOutput.insertAdjacentHTML('beforeend', "Index 2 : #{randArray[2]}<br>") # Get the last 2 indexes csOutput.insertAdjacentHTML('beforeend', "Last 2 : #{randArray[2..3]}<br>") # Defines an array with a range from 1 to 10 oneTo10 = [1..10] # You can go backwards as well tenTo1 = [10..1] # Combine Arrays combinedArray = oneTo10.concat tenTo1 # Push one tenTo1 onto the end of oneTo10 # ... is called a Splat and you use it to indicate that you want to # "soak up" a list of arguments, or all the values in the array oneTo10.push tenTo1... # Use a for loop to cycle through the array for x in oneTo10 csOutput.insertAdjacentHTML('beforeend', "#{x}<br>") # Convert an array into a String csOutput.insertAdjacentHTML('beforeend', "#{oneTo10.toString()}<br>") # Filter out all odds by saving elements that return true for the condition evensOnly = oneTo10.filter (x) -> x % 2 == 0 csOutput.insertAdjacentHTML('beforeend', "#{evensOnly.toString()}<br>") # Get the maximum value in the array csOutput.insertAdjacentHTML('beforeend', "Max : #{Math.max oneTo10...}<br>") # Get the minimum value in the array csOutput.insertAdjacentHTML('beforeend', "Min : #{Math.min oneTo10...}<br>") # Sum items in an array sumOfArray = oneTo10.reduce (x,y) -> x+y csOutput.insertAdjacentHTML('beforeend', "Sum : #{sumOfArray}<br>") # Reverse an Array csOutput.insertAdjacentHTML('beforeend', "Reverse : #{tenTo1.reverse()}<br>") # Create an array of objects peopleArray = [ { name: "Paul" age: 43 }, { name: "Sue" age: 39 }, ] # Access item by key in array csOutput.insertAdjacentHTML('beforeend', "First Name : #{peopleArray[0].name}<br>") # ---------- LOOPING ---------- # Already covered how to cycle through an array for x in oneTo10 csOutput.insertAdjacentHTML('beforeend', "#{x}<br>") # We can use the guard when to print out only odd numbers for x in oneTo10 when x%2 isnt 0 csOutput.insertAdjacentHTML('beforeend', "#{x}<br>") # We can cycle trough a range of numbers and print out the evens for x in [50..100] when x%2 is 0 csOutput.insertAdjacentHTML('beforeend', "#{x}<br>") # We can skip certain values using by for x in [20..40] by 2 csOutput.insertAdjacentHTML('beforeend', "#{x}<br>") # We can access indexes employees = [ "Doug" "Sue" "Paul" ] for employee, employeeIndex in employees csOutput.insertAdjacentHTML('beforeend', "Index: " + employeeIndex + " Employee: " + employee + "<br>") # We can search for a value with in if "Doug" in employees csOutput.insertAdjacentHTML('beforeend', "I Found Doug<br>") # Let's count from 100 to 110 with a while loop i = 100 while (i += 1) <= 110 csOutput.insertAdjacentHTML('beforeend', "i = #{i}<br>") # You can use a while loop to cycle until 0 is reached monkeys = 10 while monkeys -= 1 csOutput.insertAdjacentHTML('beforeend', "#{monkeys} little monkeys, jumping on the bed. One fell off and bumped his head.<br>") # There is no Do While loop but it can be emulated # Loop as long as x != 5 x = 0 loop csOutput.insertAdjacentHTML('beforeend', "#{++x}<br>") break unless x != 5 # ---------- FUNCTIONS ---------- # With functions always move your functions above calling them in code # You define the function name with an equal followed by attributes and -> helloFunc = (name) -> return "Hello #{name}" csOutput.insertAdjacentHTML('beforeend', "#{helloFunc("Derek")}<br>") # A function with no attributes getRandNum = -> return Math.floor(Math.random() * 100) + 1 csOutput.insertAdjacentHTML('beforeend', "Random Number : #{getRandNum()}<br>") # You can receive an undefined number of values with vars... sumNums = (vars...) -> sum = 0 for x in vars sum += x return sum csOutput.insertAdjacentHTML('beforeend', "Sum : #{sumNums(1,2,3,4,5)}<br>") # The last expression in a function is returned by default # You can define default argument values movieRank = (stars = 1) -> if stars <= 2 "Bad" else "Good" csOutput.insertAdjacentHTML('beforeend', "Movie Rank : #{movieRank()}<br>") # Recursive function that calculates a factorial factorial = (x) -> return 0 if x < 0 return 1 if x == 0 or x == 1 return x * factorial(x - 1) csOutput.insertAdjacentHTML('beforeend', "Factorial of 4 : #{factorial(4)}<br>") # 1st: num = 4 * factorial(3) = 4 * 6 = 24 # 2nd: num = 3 * factorial(2) = 3 * 2 = 6 # 3rd: num = 2 * factorial(1) = 2 * 1 = 2 # ---------- OBJECTS ---------- derek = {name: "Derek", age: 41, street: "123 Main St"} csOutput.insertAdjacentHTML('beforeend', "Name : #{derek.name}<br>") # How we add an object property derek.state = "Pennsylvania" # Cycle through an object for x, y of derek csOutput.insertAdjacentHTML('beforeend', x + " is " + y + "<br>") # ---------- CLASSES ---------- class Animal # List properties along with their default values name: "No Name" height: 0 weight: 0 sound: "No Sound" # Define a static property that is shared by all objects @numOfAnimals: 0 # Static methods also start with @ @getNumOfAnimals: () -> Animal.numOfAnimals # The constructor is called when the object is created # If we use @ with attributes the value is automatically assigned constructor: (name = "No Name", @height = 0, @weight = 0) -> # @ is like this in other languages @name = name # You access static properties using the class name Animal.numOfAnimals++ # A class function makeSound: -> "says #{@sound}" # Use @ to reference the objects properties # Use @ to call ofther methods of this object getInfo: -> "#{@name} is #{@height} cm and weighs #{@weight} kg and #{@makeSound()}" # Create an Animal object grover = new Animal() # Assign values to the Animal object grover.name = "Grover" grover.height = 60 grover.weight = 35 grover.sound = "Woof" csOutput.insertAdjacentHTML('beforeend', "#{grover.getInfo()}<br>") # You can attach new object methods outside of the class Animal::isItBig = -> if @height >= 45 "Yes" else "No" csOutput.insertAdjacentHTML('beforeend', "Is Grover Big #{grover.isItBig()}<br>") csOutput.insertAdjacentHTML('beforeend', "Number of Animals #{Animal.getNumOfAnimals()}<br>") # ---------- INHERITANCE ---------- # CoffeeScript makes inheritance very easy to implement # Each class that extends another receives all its properties and methods class Dog extends Animal sound2: "No Sound" constructor: (name = "No Name", height = 0, weight = 0) -> # When super is called in the constructor CS calls the super classes # constructor super(name, height, weight) # You override methods by declaring one with the same name # CS is smart enough to know you are calling the Animal version # of makeSound when you just type super makeSound: -> super + " and #{@sound2}" sparky = new Dog("Sparky") sparky.sound = "Wooooof" sparky.sound2 = "Grrrrr" csOutput.insertAdjacentHTML('beforeend', "#{sparky.getInfo()}<br>") |
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