Self created JS quiz with answers

js-fundamentals-answered.js

// this worksheet was generated from the 'Javascript Language Fundamentals' section of Brad Traversy's Modern Javascript Udemy course

// Variables **********************************************************************

// name 3 keywords for initializing and declaring a variable? var, let, const

// which 2 JS variable keywords are block scoped? let and const

// declare a variable but don't initialize a value.

// let name
// console.log(name)

// assign the initialized variable a value.

// name = 'John Doe'
// console.log(name)

// which type of JS variable must be both declared and initialized at the same time?  constant

// JS variables can contain what? letters,numbers,underscores,and $

// JS variables connot start with what? numbers

// Multi-word-vars. Give an example of Comel case, Underscore, and Pascal case.  which should you in JS? camelcase: firstName, underscore: first_name, pascal: FirstName

// when using const in JS, are mutatable data structures such as arrays and abjects, still mutatable? yes

// Data-Types ************************************************************************

// Name the six primitive data types in JS:
// string
// number
// boolean
// undefined
// null
// symbol

// (true or false) Null is an intentional empty value? true

// (true or false) Undefined is variable that has not been assigned a value? true

// (true or false) arrays, Object Literals, Functions, and Dates are considered Reference Data Types? true

// what can be used to find out a variable's type? typeof()

// Type conversion *******************************************************************

// Use the String function to convert a number, boolean, date, and an array to a string
// let item = 5
// item = true
// item = ['mon', 'tues', 'wed']
// item = new Date()

// item = String(item)

// console.log(item)
// console.log(typeof item)

// Use the toString method to convert a number to a string

// let item = 8
// item = item.toString()
// console.log(item)
// console.log(typeof item)

// Use the Number function to convert a string-number, both booleans, and a word string to a number

// let it = '9'
// it = true
// it = false
// it = 'word'

// it = Number(it)

// console.log(it)
// console.log(typeof it)

// (true or false) NaN is a value that means not a number. true

// (true or false) NaN is what is output when a value can't be converted to a number. true

// besides the Number() function, show 2 more ways to convert to a number, using the functions parseInt() and parseFloat()

// it = '33'
// it = '39.3376'
// it = parseInt(it)
// it = parseFloat(it)
// console.log(it, typeof it)
// console.log(it.toFixed(2), typeof it)

// (true or false) the toFixed method can be used to add decimal places to a number. true

// Type coersion *******************************************************************

// (true or false) type coersion is when JS automatically does type conversion on a value.  this can be unwanted, so you need to be alert to this possibility when coding? true

// The Math Object *****************************************************************

// use the following methods on the Math object to generate results.

// Math.round()
// Math.ceil()
// Math.floor()
// Math.sqrt()
// Math.abs()
// Math.pow()
// Math.min()
// Math.max()
// Math.random()

// let num

// num = Math.round(12.7)
// num = Math.ceil(12.1)
// num = Math.floor(12.9)
// num = Math.sqrt(64)
// num = Math.abs(-59)
// num = Math.pow(8, 2)
// num = Math.min(64, 55, 33)
// num = Math.max(64, 55, 33)
// num = Math.random() * 100
// num = parseInt(num)

// console.log(num)

// String methods & Concatenation ******************************************************

// give an example of string concatenation

// let name = 'Tom'
// let secondName = 'Smith'

// console.log(name + ' ' + secondName)

// append 2 string variables using the += (addition assignment operator) which means x = x + y

// name += secondName
// console.log(name)

// give an example of escaping characters

// let phrase = 'Tom replied: Let\'s study at my house'
// console.log(phrase)

// use the following methods and properties on strings

// length

// let email = 'john@yahoo.com'
// console.log(email + ' is ' + email.length + ' letters long.')

// concat()

// let work = ' driver'
// console.log(email.concat(work))

// toUpperCase()

// console.log(email.toUpperCase())

// toLowerCase()

// let caps = 'HELLO'
// let smalls = caps.toLowerCase()
// console.log(smalls)

// get character using []

// console.log(smalls[2])

// indexOf()

// let big = 'supercalafragilistic'
// console.log(big.indexOf('c'))

// // lastIndexof()  (this comes from the end of the string)

// console.log(big.lastIndexOf('c'))

// // charAt()

// console.log(big.charAt(9))

// // Get last character of a string by using charAt(yourstring.length -1)

// console.log(big.charAt(big.length - 1))

// // substring(0, 4)

// let sub = big.substring(0, 4)
// console.log(sub)

// // slice(0, 4)  slice works with strings and arrays... with slice you can use negative numbers and it will begin at the back of the string or array

// let slice = big.slice(0, -4)
// console.log(slice)

// split() split will turn the string into an array. you can split on any character including spaces.

// let phrase = 'this is my string'
// let newPhrase = phrase.split(' ')
// console.log(newPhrase)

// // replace()

// console.log(phrase.replace('my', 'your'))

// // includes()  check if the string or char exists inside of a string. returns true or false

// console.log(phrase.includes('string'))

// // Template Literals *****************************************************************

// // take the following data and input it as an unordered list in html (do this using string concatenation and template literals)

// const obj = {
//   name: 'John',
//   age: 30,
//   job: 'Web Developer',
//   city: 'Miami'
// }

// let concat = '<ul> <li>name: ' + obj.name + '</li> <li>age: ' + obj.age + '</li> <li>job ' + obj.job + '</li> <li>city: ' + obj.city + '</li> </ul>'

// console.log(concat)

// let data = `<ul>
//   <li>name: ${obj.name}</li>
//   <li>age: ${obj.age}</li>
//   <li>job: ${obj.job}</li>
//   <li>city: ${obj.city}</li>
// </ul>`

// console.log(data)

// // output an expression using template literals

// let add = `5 + 5 = ${5 + 5}`
// console.log(add)

// // output a function using template literals

// const hello = function () {
//   return 'hello'
// }
// const literal = `I'm literally saying ${hello()}`

// console.log(literal)

// // output conditional or 'if statement' using template literals. You must use ternary operator syntax or wrap the 'if statement in a called anonymous function

// let age = 40
// let sentence = `Bob is ${age < 39 ? 'young' : 'old'}`
// console.log(sentence)

// // ex. ternary-operator: `${age > 30 ? 'Over 30' : 'Under 30'}

// // ex. invoked anon function if-statement:
// // const age = 30
// // let html = `<div>
// //     ${
// //       (age => {
// //         if(age > 30) {
// //           return 'Over 30'
// //         } else {
// //           return 'Under 30'
// //         }
// //       })()
// //     }
// //   </div>`
// // document.body.innerHTML = html

// let sentence2 = `Bob is ${
//   (age => {
//     if (age < 39) {
//       return 'young'
//     } else {
//       return 'old'
//     }
//   })()
// }`

// console.log(sentence2)

// Arrays and Array Methods *************************************************************

/* ~~~~~~~~~~~~ examples
ex. const numbers = [43,56,13,81,61]
ex. const numbers2 = new Array(22,45,33,17,12)
ex. numbers.length
ex. Array.isArray(numbers)
ex. numbers[3]
ex. numbers[2] = 100
ex numbers.indexOf(61)
ex. numbers.push(250)
ex. numbers.unshift(120)
ex. numbers.pop()
ex. numbers.shift()
ex. numbers.splice(1,1)
ex. numbers.reverse()
ex. numbers.concat(numbers2)
ex. fruit.sort()
ex. numbers.sort()
ex. numbers.sort(function (x, y){
  return x - y
})
ex. numbers.sort(function (x, y){
  return y - x
})
ex. finds the 1st number under 50
function under50(num) {
  return num < 50
}
numbers.find(under50)
ex. finds the 1st number over 50
function overr50(num) {
  return num > 50
}
numbers.find(over50)
~~~~~~~~~~~~~~~~~~~~~~~~~ */

// // create an array using an array literal:

// const list = ['eggs', 'bacon', 'ham', 'bread']
// console.log(list)

// // create an array using an array constructor:

// const groceries = new Array('eggs', 'bacon', 'tomatoes', 'gravy')
// console.log(groceries)

// // Create some arrays with numbers, strings, mixed data types:

// const nums = [3, 5, 17, 33]
// const strings = ['rock', 'opera', 'bluegrass', 'country', 'hip-hop']
// const mixed = [7, 'eleven', {car: 'chevy'}, ['stop', 'drop', 'roll'], 79, true, null, 'end']

// console.log(nums)
// console.log(strings)
// console.log(mixed)

// // Get array length:

// console.log(mixed.length)

// // Check if is array:

// console.log(Array.isArray(mixed[3]))

// // Get single value:

// console.log(nums[2])

// // Insert into array:

// nums[2] = 19
// console.log(nums)

// // Find index of value:

// let singleNum = nums.indexOf(33)
// console.log('index: ', singleNum)

// // ------MUTATING ARRAYS----------

// // Add on to end:

// nums.push(99)
// console.log(nums)

// // Add on the front:

// nums.unshift(45)
// console.log(nums)

// // Take off from end:

// nums.pop()
// console.log(nums)

// // Take off from front:

// nums.shift()
// console.log(nums)

// // Splice values:

// let miniNums = nums.splice(1, 1, 6, 7, 8)
// console.log(miniNums + '\n' + nums)

// // Reverse:

// nums.reverse()
// console.log(nums)

// // Concatenate array:

// let newNums = nums.concat(4, 11)
// console.log(newNums)

// // ------Sorting arrays------

// // string array, sorts by alpha:

// strings.sort()
// console.log(strings)
// strings.reverse()
// console.log(strings)

// // num array, sorts by first number:

// nums.sort()
// console.log(nums)

// // use the "compare function" for least to greatest:

// nums.sort((x, y) => {
//   return x - y
// })
// console.log(nums)

// // use the "compare function" for greatest to least:

// nums.sort((x, y) => {
//   return y - x
// })
// console.log(nums)

// // Find: find the 1st number under 50

// function under50 (num) {
//   return num < 50
// }
// console.log(nums.find(under50))

// // Find: find the 1st number over 50

// nums.push(79)

// function over50 (num) {
//   return num > 50
// }
// console.log(nums.find(over50))

// Object Literals *****************************************************************

// // Create an object literal containing the following property-types: string, number, array, abject, function

// let person = {
//   firstName: 'Rob',
//   LastName: 'Love',
//   age: '37',
//   interests: ['sports', 'motorcycles', 'carpentry'],
//   address: {
//     city: 'Chicago',
//     state: 'IL'
//   },
//   sayName: function () {
//     return `Hi, my name is ${this.firstName}`
//   }
// }
// console.log(person)

// // Get a specific value from each property using dot-notation. give an example of bracket-notation:

// console.log(person.LastName)
// console.log(person.age)
// console.log(person['firstName'])
// console.log(person.interests)
// console.log(person.interests[1])
// console.log(person.address)
// console.log(person.address.city)
// console.log(person.sayName())
// console.log(person['interests'][[2]])

// // Create a method on the object that uses the this keyword:

// person.sayAge = function () {
//   console.log(`I am ${this.age} years old`)
// }
// person.sayAge()

// // Create an array of object literals:

// let team = [{name: 'Jerry', position: 'Manager'}, {name: 'Rena', position: 'clerk'}, {name: 'Ron', position: 'clerk'}]

// console.log(team)

// Dates and Times ******************************************************************

// If Statements and Comparison operators *******************************************

// // Create example if, if/else, and else if statements with the following...
// // Equal To: ==

// let one = 1
// if (one == true) {
//   console.log('this is true')
// }

// // Not Equal To: !=

// if (one != true) {
//   console.log('this is true')
// } else {
//   console.log('this is not true')
// }

// // Equal to value and Type: ===

// let one2 = '1'
// if (one === one2) {
//   console.log(`${one} is equal to ${one2} in both value and type`)
// } else {
//   console.log(`one, value:${one} type:${typeof one}`)
//   console.log(`one2, value:${one2} type:${typeof one2}`)
// }

// // Not Equal to value and Type: !==

// let word = 'big'
// let word2 = 'big'

// if (typeof word !== typeof word2) {
//   console.log('the variables are not equal in type')
// } else {
//   console.log('the variables are equal in both value and type')
// }
// // Check to see if variable undefined: typeof varName !== 'undefined'

// const person = undefined

// if (person !== undefined) {
//   console.log('the variable is not equal to undefined')
// } else {
//   console.log('they are equal')
// }

// // Greater or Less than:

// if (57 < 33) {
//   console.log('57 is less than 33')
// } else {
//   console.log('57 is greater than 33')
// }

// // Else if:

// let myFavCar = 'gmc'

// let car1 = 'ford'
// let car2 = 'honda'
// let car3 = 'gmc'

// if (car1 === myFavCar) {
//   console.log(`${car1} is the car for me`)
// } else if (car2 === myFavCar) {
//   console.log(`${car2} is the car for me`)
// } else if (car3 === myFavCar) {
//   console.log(`${car3} is the car for me`)
// }

// // Logical Operators:
// // AND &&

// if (car3 === myFavCar && car1 !== myFavCar) {
//   console.log('that\'s right')
// }

// // OR ||

// if (car1 === car2 || car2 === car3) {
//   console.log('one of these statements is true')
// } else {
//   console.log('both of these statements are false')
// }

// // Shorthand:
// // TERNARY OPERATOR: ? (if), : (else)

// let scoreOne = 99
// let scoreTwo = 79

// scoreOne > scoreTwo ? console.log('scoreOne!') : console.log('scoreTwo!')

// // if/else Without Braces:

// if (scoreOne === scoreTwo)
//   console.log('Tie')
// else
//   console.log('We have a winner')

// // Switch Statements ******************************************************************

// // Create a switch statement with several cases:

// let day = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday']

// switch (day[2]) {
//   case 'Monday':
//     console.log('work @ 7am')
//     break
//   case 'Tuesday':
//     console.log('work @ 8am')
//     break
//   case 'Wednesday':
//     console.log('work @ 9am')
//     break
// }

// // Functions, function Declarations and function Expressions **************************

// // Function Declarations example:

// function Callme () {
//   return 'Hello there, what can I do for you?'
// }

// console.log(Callme())

// // function with parameters & multiple parameters:

// function double (val) {
//   if (typeof val === typeof 'string') {
//     return val.append(' ' + val)
//   } else if (typeof val === typeof 5) {
//     return val * 2
//   } else {
//     return 'I can\'t handle this type'
//   }
// }

// console.log(double(8))

// // default values for parameters example:

// const fullName = (first = 'John', last = 'Doe') => {
//   return `Congratulations, your full name is ${first} ${last}!`
// }
// console.log(fullName('Ben', 'Faught'))

// // function expression example:

// const hello = function () {
//   console.log('hello world!')
// }
// hello()

// // named function expression:

// const multiply = function multiply (num, multiplier) {
//   return num * multiplier
// }
// console.log(multiply(7, 3))

// // Immediately Invoked Function Expressions - IIFEs:

// (function () {
//   console.log('I am an IIFE :)')
// })();

// // IIFE with params:

// (function (name) {
//   console.log('I am an IIFE with params, my name is ' + name)
// })('Biffie');

// // TRUE or False, in modules, IIFEs can provide private methods and properties, by keeping everything scoped to that module? true

// // Property Methods... Create a method within an object:

// let myObj = {
//   name: 'Larry',
//   age: 30,
//   iam: function () {
//     console.log(`my name is ${this.name} and I am ${this.age} years old.`)
//   }
// }

// myObj.iam()

// // Create a method on an object from outside the object:

// myObj.hello = function () {
//   console.log(`this is ${this.name}, just saying hello!`)
// }

// myObj.hello()

// General Loops ************************************************************************

// // create a general for loop:

// for (let i = 0; i < 5; i++) {
//   console.log('the count is: ' + i)
// }

// // for loop with a condition inside that uses the continue keyword:

// for (let i = 0; i < 15; i++) {
//   if (i >= 5 && i < 10) {
//     console.log('continue: ' + i)
//     continue
//   }
//   console.log('the count is: ' + i)
// }

// // for loop with a condition inside that uses the break keyword:

// for (let i = 0; i < 10; i++) {
//   if (i === 6) {
//     console.log('I\'m leaving this loop at 6')
//     break
//   }
//   console.log('looping @: ' + i)
// }

// // create a while loop:

// let m = 0

// while (m <= 3) {
//   console.log('value is: ' + m)
//   m++
// }

// // true or false, a do-while loop will run it's first iteration regardless of the conditional. true

// // create a do while loop:

// do {
//   console.log('hello')
//   m++
// } while (m < 1)

// // use a for loop to iterate through an array: hint: array.length

// let list = ['eggs', 'milk', 'bread', 'bologna']

// for (let i = 0; i < list.length; i++) {
//   console.log(list[i])
// }

// // use forEach() to loop through an array:

// const users = [
//   {id: '7', first: 'Tom', last: 'Brady'},
//   {id: '8', first: 'Mary', last: 'Smith'},
//   {id: '9', first: 'Jake', last: 'Paul'}
// ]

// users.forEach(function (user) {
//   console.log(user.last)
//   console.log(user)
// })

// // use forEach() to loop through an array, using the index & array keyword as a parameter in the callback:

// users.forEach(function (user, index, array) {
//   console.log(user.first)
//   console.log(index)
//   console.log(array)
// })

// // use map() to loop through an existing array of objects, and create an new array from one of the properties of that object:

// const ids = users.map(function (user) {
//   return user.id
// })
// console.log(ids)

// // create a for-in loop on an object literal (print out both the key and value):

// const person = {
//   name: 'Bob',
//   age: 'White',
//   dob: '11-3-1977',
//   city: 'New York'
// }

// for (let x in person) {
//   console.log(x)
//   console.log(person[x])
//   console.log(`${x}: ${person[x]}`)
// }