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...

1. Update your printNums function to take a num paramater, then update your code to only print the numbers 0 through num.
2. Update your printNums function to take 2 paramaters. The first paramater is the starting number and second will be the ending number (inclusive).
3. Write a function named sumAll that will take 0 or more arguments, and return the sum of all arguments. Hint: lookup the arguments keyword.
4. Write a function called times2, that takes a number as input and returns this number multiplied by 2.
5. What would the result of the following code be? times2(times2(3))
6. 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...