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Self created JS quiz with answers
// 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]}`)
// }
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