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TTI > PB > Flashcards

PB Flashcards

1
Q

What are the differences between objects and arrays? What is the purpose of the object and what is the purpose of the array?

A
  • An object can store multiple properties with key names, while an array can store a list of items that are usually of the same type (e.g., all numbers or all strings).
  • You can access an object’s property using the property’s key name, while you access an array’s element using its index.
  • Objects are typically used to store properties that describe something, like the attributes of a book (name, author, price, etc.).
  • Arrays are commonly used to store lists of data, like a group of ages or a collection of objects (e.g., books).
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2
Q
  • How can you access a key’s value in an object?
A
  • There are two ways:
    - objectName.keyName
    - objectName["keyName"]
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3
Q
  • How can you access the first and the last item of an array? (JS)
A
  • First element: arrayName[0]
  • Last element: arrayName[arrayName.length - 1]
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4
Q
  • Name all the primitive types in JavaScript.
A
  • number, bigint, string, boolean, undefined, null, symbol
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5
Q
  • What are the assignment operators? Name some of them.
A
  • Assignment (=)
  • Addition assignment (+=)
  • Subtraction assignment (-=)
  • Multiplication assignment (*=)
  • Division assignment (/=)
  • Modulus assignment (%=)
  • Exponentiation assignment (**=)
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6
Q
  • What are the arithmetic operators? Name some of them.
A
  • Addition (+)
  • Subtraction (-)
  • Multiplication (*)
  • Division (/)
  • Modulus (%)
  • Increment (++)
  • Decrement (--)
  • Exponentiation (**)
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7
Q
  • What are the comparison operators? Name some of them.(JS)
A
  • Equal to (==)
  • Strict equal to (===)
  • Less than (<)
  • Greater than (>)
  • Less than or equal to (<=)
  • Greater than or equal to (>=)
  • Not equal (!=)
  • Not equal value or type (!==)
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8
Q
  • What are the logical operators? Name some of them.
A
  • And (&&)
  • Or (||)
  • Not (!)
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9
Q
  • What is the difference between for, for of and for in?
A
  • for is a loop used to execute a block of code a certain number of times.
  • for...of loops through the values of iterable objects like arrays, strings, sets, and maps.
  • for...in loops through the properties of an object.
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10
Q
  • How do you find the average of values in an array if you can’t use any built-in functions or methods?
A 
let sum = 0;
for (let value of array) {
  sum += value;
}
let average = sum / array.length;
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11
Q
  • What are the main parts of a function?
A
  • Parameters, the function body, and arguments.
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12
Q
  • What is the difference between parameters and arguments?
A
  • Parameters are placeholders in the function’s declaration, while arguments are the actual values passed to the function when it’s called.
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13
Q
  • What are the differences between function expression and function statement?
A
  • Function expression: var foo = function() {...};
  • Function declaration: function foo() {...};
  • Function declarations are hoisted and can be used before their declaration. Function expressions are not hoisted and can’t be used before their declaration.
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14
Q
  • What is a method?
A
  • A method is a function that belongs to an object or a class.
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15
Q
  • Name 3 builtin functions (and/or methods) regarding strings.
A
  • str.length
  • str.split()
  • str.slice()
  • Str.repeat()
  • Str.search()
  • Str.toUpperCase()
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16
Q
  • Name 3 builtin functions (and/or methods) regarding arrays.(JavaScript)
A
  • arr.length
  • arr.slice()
  • arr.push()
  • Arr.pop()
  • Arr.splice()
  • Arr.join()
  • Arr.indexOf()
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17
Q
  • Name 3 builtin functions (and/or methods) regarding numbers.
A
  • num.toFixed()
  • num.toPrecision()
  • Nr.toString()
  • Number()
  • parseInt()
  • parseFloat()
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18
Q
  • What is a callback function?
A
  • A callback function is a function passed as an argument to another function and is executed after the completion of that function.
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19
Q
  • What are the differences between for loops and forEach?
A
  • A for loop is a general-purpose loop for iterating over values multiple times.
  • forEach is a higher-order function used to iterate over elements of an array and execute a callback function on each element.
20
Q
  • What is the difference between JavaScript data structures and JSON data structures?
A
  • JavaScript data structures are in-memory representations of objects, arrays, strings, etc.
  • JSON data structures are string representations of data, used for data interchange.
21
Q
  • How do you create JavaScript data structure from a JSON file’s data?
A 
import * as fs from "node:fs";
let dataStructure = JSON.parse(fs.readFileSync("fileName.json", "utf8"));
22
Q
  • What is the difference between JavaScript data structures and DOM (HTML document) data structures?
A
  • JavaScript data structures are used to store and manipulate data in memory.
  • DOM data structures represent the structure of HTML documents and allow manipulation of the document’s content.
23
Q
  • What are the steps of changing a HTML element’s content with JavaScript?
A
  • Get the element using getElementById or querySelector.
  • Use properties like innerHTML, textContent, or insertAdjacentHTML to modify the content.
24
Q
  • What is an event listener?
A
  • An event listener is a built-in function that waits for a specific event to occur on an element and triggers a callback function in response.
25
Q
  • What are the steps of changing a HTML element’s content when the element clicked?
A
  • Create an event listener using addEventListener.
  • Inside the event listener, modify the element’s content using innerHTML or other properties.
26
Q
  • Inside a click event listener, how can you access the element that has been clicked?
A
  • By using the event object passed to the event listener function, often referred to as event or e.
27
Q
  • What are the differences between display: block and display: inline CSS properties?
A
  • display: block makes an element a block-level element, taking up the entire width of its parent and stacking vertically.
  • display: inline makes an element an inline-level element, allowing other elements to sit beside it on the same line.
28
Q
  • What are the differences between position: relative and position: absolute CSS properties?
A
  • position: relative positions an element relative to its normal position.
  • position: absolute positions an element relative to its closest positioned ancestor.
29
Q
  • What is the box model, name the CSS properties connecting to it?
A
  • The box model describes how elements are rendered in terms of their content, padding, border, and margin.
  • Related properties: margin, padding, border, width, height, box-sizing.
30
Q
  • What CSS properties affect font and text appearance?
A
  • color, font-size, font-weight, font-family, line-height, text-align, text-transform.
31
Q
  • What are the steps of adding or removing a HTML element’s class name?
A
  • Adding: element.classList.add("className")
  • Removing: element.classList.remove("className")
32
Q
  • Is null an object or a primitive?
A
  • It is a primitive value and represents the absence of any value.
33
Q
  • What is undefined?
A
  • undefined is a special value indicating that a variable has been declared but hasn’t been assigned a value.
34
Q
  • What does it mean that a data type is mutable and what does it mean that it is immutable? Mention some examples.
A
  • Mutable data types can be changed after creation. Examples include arrays and objects.
  • Immutable data types cannot be changed after creation. Examples include strings and numbers.
let mutableArray = [1, 2, 3];
mutableArray[0] = 10;
console.log(mutableArray); // Output: [10, 2, 3]
let immutableString = "Hello";
immutableString[0] = "W"; // This won't change the string
console.log(immutableString); // Output: "Hello"
let immutableNumber = 42;
immutableNumber = 99; // This reassigns the variable
console.log(immutableNumber); // Output: 99
35
Q
  • What does it mean that a data type is passed by value and what does it mean that it is passed by reference? Mention some examples.
A
  • Passed by value means that a copy of the value is passed to a function. Primitives are passed by value.
  • Passed by reference means that a reference to the original value is passed to a function. Objects are passed by reference.
36
Q
  • When to use var, let, and const?
A
  • Use var for legacy code or when you need function scope (not recommended in modern code).
  • Use let for variables that will be reassigned.
  • Use const for variables that won’t be reassigned.
37
Q
  • What is hoisting?
A
  • Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope during compilation.
38
Q
  • What are the advantages of using a version control system?(git)
A
  • Version control helps track changes, collaborate effectively, manage project history, and revert to previous states.
39
Q
  • What’s the difference between Git and GitHub?
A
  • Git is a version control system for tracking changes in code.
  • GitHub is a platform that provides hosting for Git repositories and additional collaboration features.
40
Q
  • What are remote repositories in Git?
A
  • Remote repositories are versions of a project that are hosted on a different server.
41
Q
  • Why does a merge conflict occur?
A
  • A merge conflict occurs when changes made in two different branches of a repository cannot be automatically merged.
42
Q
  • How do you run a JavaScript file in the terminal?
A
  • Use the command: node <filename>.js
43
Q
  • How do you stop a running a command in the terminal?
A
  • Press Ctrl+C
44
Q
  • How go you get the previous command in the terminal?
A
  • Use the up arrow key or press Ctrl+R
45
Q
  • How do you got to the current directory’s parent directory in the terminal?
A
  • Use the command: cd ..

TTI (6 decks)

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