js-review.js

/*
named functions inside objects are called methods
*/

function returnAnObject(name, age) {
   const myObject = {
     myName: name,
     myAge: age,
     sleep: function() {
        console.log('zzzzz')
     }
   }

   return myObject
}

const arjun = returnAnObject('Arjun', 34)
// { myName: 'Arjun', myAge: 34, sleep: [function]}
arjun.myName
// 'Arjun'
arjun.myAge
// 34
arjun.sleep
// [Function]
arjun.sleep()
// 'zzzzz'

/*
how to update an Object that is passed in as an argument
to a function
*/

function updateObject(input) {
  // const input = {name: 'Arjun', age: 34}
  input.name = 'Bethany'
  input.foo = 'foo'
  input.bar = 'bar'
  input.pow = 'wow'
  return input
}

updateObject( {name: 'Arjun', age: 34} )
// {name: 'Bethany', age: 34, foo: 'foo', bar: 'bar', pow: 'wow}


/*
when you pass in data to a function when running it, that data
is provided inside the function block (stuff inside these {}) 
as a local variable, named whatever it was named when you made
the function
*/
function sayName(name) {
  // const name = 'Bethany'
  console.log(name)
}

sayName('Bethany')


/*
Functions should take it ALL the data they need as input arguments.
They should almost never rely on variables that were set outside of
the function, because those variable can change in value, and then
your function ends up having multiple different results even with
the same input arguments. This is BAD! for any given set of input args
the function should have one and only one consistent output for each
set
*/

function add (num1, num2) {
  return num1 + num2
}

add(4, 6)
// 10


// BAD

let number = 6

function addThreeToNumber () {
   number + 3
}

addThreeToNumber()
console.log(number)
// 9

addThreeToNumber()
console.log(number)
// 12

addThreeToNumber()
console.log(number)
// 15

// GOOD

function addThreeToNumber (thisNumber) {
  return thisNumber + 3
}

addThreeToNumber(6)
// 9

addThreeToNumber(6)
// 9

addThreeToNumber(10)
// 13


/*
how to deal with object keys with spaces in them. Don't do this
yourself, but you may have to deal with this if you are working
with other people's data
*/

const dog = {
  name: 'Bow wow',
  breed: 'Tibetan Mastiff',
  dateOfBirth: '2019/04/01',
  sizeOfPaw: 'large',
  'badly name key': 'BAD'
}

dog.name
// 'Bow wow'
dog.dateOfBirth
// '2019/04/01'
dog['name']
// 'Bow wow'
dog.badly named variable
// ERROR THIS DOES NOT WORK
dog['badly named variable']
// 'BAD'




/*
String interpolation / template strings (strings that use ``)
` - are called backticks
they also allow for multi-line string!
allows more elegant insertion of JS into string
*/


const name = 'Bethany'
const favoriteColor = 'brown'

console.log('my name is ' + name + ' and my favorite color is ' + favoriteColor)
// 'my name is Bethany and my favorite color is brown

console.log(`my name is ${name}
and my favorite color is ${favoriteColor}
and one plus one is ${1+1}`)

// my name is Bethany
// and my favorite color is brown
// and one plus one is 2