Fundamentals Flashcards

Question

The Ternary Operator

Answer 1

If/Else statement without If/Else Item 1 >= Item 2 ? True : False

Answer 2

1) What do we want to calculate? (birthYear) 2) Draw an Arrow (=>) 3) What do we want to return? (2037 - birthYear) 4) Store it in a variable (const calcAge) 5) Put it together const calcAge = birthYear => 2037 - birthYear

Answer 3

Objects are created like arrays with {} instead of []. Each item is named with parameters too. Example: const john = { name: ‘John Smith’, weight: 92, height: 1.95, }; REMEMBER: every line gets a comma

Answer 4

A method is essentially a function ran inside of an object. Instead of defining full parameters though, we use “this” and the parameters from inside of the object. Example: const john = { name: "John smith", weight: 92, height: 1.95, calcBMI: function () {return this weight / this.height ** 2;}, }; Note: methods will not call themselves. You have to later call them to get a property out of them if you create a property within them.

Answer 5

One of two ways: 1) use the object name.new property ex: mike.dog = ‘Taco’ would add “dog: ‘Taco’ to the mike object. 2) create it as part of a method. Ex: calcAge: function() { this.age = 2037 - birthYear; return this.age; } In this case, “age” is being added to the object this method belongs to.

Answer 6

function functionName(parameter) { return what we want the function to do; }

Answer 7

const functionName = function (parameter) { item 1 >= item 2 ? True : False; } Can’t be used for every function but for true/false or “If this then that” statements, it works.

Answer 8

for (let i = 0; i < item.length; i++) { Return what we want it to do during the loop }

Answer 9

Using the Spread Operator const data1 = [17, 21, 23]; const data2 = [12, 5, -5, 0, 4] const data = […data1, …data2]

Answer 10

1) Add all of the values of the array into an accumulator variable (starting at ‘ ‘ because the string is empty; literally called empty string) let string = ‘ ‘ 2) In each iteration, we will add the current value of the array string = current value of string + array at the current position (str += ‘${array[i]}’)

Answer 11

In-line JavaScript

Answer 12

Statements are the list of instructions to be executed by the computer that make up a program.

Answer 13

A value that can be altered, depending on conditions or data passed to the program.

Answer 14

Adding a backslash (\) tells the computer that the character that follows has a special meaning. Example: \’ or \” means that the quotations after the slash is not meant to end the string but to be printed.

Answer 15

“br” stands for “break” as in “line break”. It means the same as hitting “enter” only in the code.

Answer 16

Element.replace(‘grey’,’gray’)

Answer 17

Element.replaceAll(‘grey’,’gray’)

Answer 18

Functions we previously created that we “call back” during higher order functions.

Answer 19

.replace(/_/g, ‘ ’) The “g” stands for “Global”. In this example, every underscore is replaced with a space in that parameter.

Answer 20

prompt() prompt(message) prompt(message, defaultValue) This instructs the browser to display a dialog box with an optional message prompting the user to input some text and either confirm or cancel the dialog.

Answer 21

First part of the line is the location we want to click (in this case we'll call it "btnSort"). btnSort.addEventListener('click', what we want to happen when we click).

Answer 22

Joins a string back together (opposite of "split")

Answer 23

Splits a string into multiple parts based on a divider Can do the same thing with the “slice” method but that is for very short phrases and is a bit more complicated to implement.

Answer 24

manually set "this" keyword but don’t immediately call; creates a new function where “this” is bound Const bookEW = book.bind(eurowings) Lesson: we defined an object (lufthansa) and within the object created a function (lufthansa.book). Later, we invoked that function using the call method under a different object (eurowings). Now, instead of using the call method where we have to specify where the “this” points to we simply bind that property to the new variable.

Answer 25

Tells the function that the next parameter is where “this” should point to. function greet() { console.log(this.animal, "typically sleep between", this.sleepDuration); } const obj = { animal: "cats", sleepDuration: "12 and 16 hours", }; greet.call(obj); // cats typically sleep between 12 and 16 hours

Answer 26

Tells the array that the next parameter is where "this" should point to. const array = ["a", "b"]; const elements = [0, 1, 2]; array.push.apply(array, elements); console.info(array); // ["a", "b", 0, 1, 2]

Answer 27

Element.padStart

Answer 28

Element.padEnd

Answer 29

Element.toLowerCase()

Answer 30

Element.toUpperCase()

Answer 31

Element.startsWith() is a true/false statement regarding what boolean an element starts with Does monkey start with an m? Yes So element.startswith(m) would be true

Answer 32

Element.endsWith() is a true/false statement regarding what boolean an element ends with Does monkey end with a y? Yes So element.endswith(y) would be true

Answer 33

indexOf is used to simply find something within something else. const airline = 'TAP Air Portugal'; console.log(airline.slice(0, airline.indexOf(' '))); It returns "TAP" as the parameter is basically a wild-card search to return whatever is at position 0, in this case it is TAP.

Answer 34

lastIndexOf() finds the last occurrence of something inside a particular parameter. CASE SENSITIVE const airline = 'TAP Air Portugal'; console.log(airline.slice(airline.lastIndexOf(' ') + 1)); Returns "Portugal"

Answer 35

Creates a shallow copy of an array into a new array at particular points const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"]; const citrus = fruits.slice(1, 3); // fruits contains ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'] // citrus contains ['Orange','Lemon'] (Remember, the "end" number is the item before the end. So 1, 3 means item one (orange) and the item BEFORE 3 (lemon).)

Answer 36

(function (a) { return a + 100 }); 1) Remove the word “function”. 2) Place an arrow between the argument and the opening body bracket. 3) Remove the body braces and “return”. 4) Remove the parameter parenthesis. a => a + 100

Answer 37

Map creates a brand new array copy of the original array (it "maps" the values of the original). Can be used to loop over arrays; more useful than for/each method. const movements = [200, 450, -400, 3000, -650, -130, 70, 1300]; const eurToUsd = 1.1; const movementsUSD = movements.map(mov => mov * eurToUsd); Will now return a new array with the "movements" converted from Euros to US dollars.

Answer 38

filter() creates a shallow copy of a portion of a given array, filtered down to the elements that pass the test we created within the function const words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present']; const result = words.filter(word => word.length > 6); console.log(result); // Expected output: Array ["exuberant", "destruction", "present"]

Answer 39

It’s an assignment operator that sets the variable to the left to the value of the expression to the right. a = 10 works 10 = 10 / ‘a’ = 10 / ‘a’ = ‘a’ doesn’t.

Answer 40

A comparison operator which transforms the operants to the same type before comparison. 10 == ‘10’ works

Answer 41

Strict equality comparison operator which compares one for one. They need to match exactly. ‘2’ === 2 is false 2 === 2 is true

Answer 42

includes() method determines whether an array includes a certain value among its entries, returning "true" or "false". const pets = ['cat', 'dog', 'bat']; console.log(pets.includes('cat')); true console.log(pets.includes('at')); false