Functions Lesson Notes

Functions.md

Functions

Objectives

• Define what an abstractions is
• Explain why abstractions are useful
• Define what a function is and why they are useful
• Describe why functions are abstractions
• Explain the syntax of functions

Terms

• Function Declaration
• Function Expression
• Anonymous Function
• Paramater
• Argument
• Invoke

Guiding Questions

• What are abstractions? With your table, create a definition of what an abstraction is. Also, describe one abstraction that you have worked with.

  Your answer...

• Why are abstraction useful? With your table, synthesize an explanation of why abstractions are useful. Add an example of when an abstraction helped you be more productive.

  Your answer...

• Define what a function is and why they are useful.

  Your answer...

• Why are functions abstractions?

  Your answer...

• Explain the syntax of a function.

  Label the following code with all the function termanology that you know!

  1) keyword
  2) name
  3) body
  4) parameters
  5) arguments
  6) invokation
  

  function sayHi(name) {
    return `Hello, ${name}`
  }
  
  sayHi('Mossy')

  Your answer...

• How are function declarations different from function expressions?

  Your answer...

• What is the difference between these two functions?

  function boom () {
    console.log('BOOM!')
  }
  
  function boom () {
    return 'BOOM!'
  }

  Your answer...

Practicing Functions

In a scratch javascript file write the code for the following functions. Compare your work with your neighbor.

• Update the following code to use a function.

  var names = [ 'Erik', 'Sarah', 'Nancy', 'Matt' ]
  if (names.length > 0) {
    var selected = names.shift()
    console.log(selected)
  }
  if (names.length > 0) {
    var selected = names.shift()
    console.log(selected)
  }
  if (names.length > 0) {
    var selected = names.shift()
    console.log(selected)
  }

  Your answer...

• Write a function called printNums that prints out the numbers 0 through 9.

  Your answer...

• Update your printNums function to take a num paramater, then update your code to only print the numbers 0 through num.

  Your answer...

• Update your printNums function to take 2 paramaters. The first paramater is the starting number and second will be the ending number (inclusive).

  Your answer...

• Write a function named sumAll that will take 0 or more arguments, and return the sum of all arguments. Hint: lookup the arguments keyword.

  Your answer...

• Write a function called times2, that takes a number as input and returns this number multiplied by 2.

  Your answer...

• What would the result of the following code be? times2(times2(3))

  Your answer...

• Looking at the code bellow, what order will we see the the logs?

  function boom() {
    console.log('BOOM!')
  }
  
  function bang() {
    console.log('BANG!')
  }
  
  
  function pow() {
    console.log('POW!')
  }
  
  
  boom(bang(pow()))

  Your answer...