JavaScript Quiz Questions
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Questions and Answers

What does the 'Promise' object in JavaScript primarily do?

  • To create event listeners
  • To manipulate HTML elements
  • To handle asynchronous operations and their results (correct)
  • To define conditional statements

    • Which method is used to add a new element at the beginning of an array in JavaScript?

  • prepend()
  • push()
  • shift()
  • unshift() (correct)

    • What is the main functionality of the 'localStorage' object in JavaScript?

  • Access the user's location
  • Manipulate the DOM
  • Store data locally within the user's browser (correct)
  • Perform asynchronous operations

    • What is the purpose of the 'fetch' API in JavaScript?

    <p>To make HTTP requests and handle responses asynchronously</p> Signup and view all the answers

    What does the 'typeof' operator do in JavaScript?

    <p>Returns the type of a variable or expression</p> Signup and view all the answers

    How can you add a new element to the end of an array in JavaScript?

    <p>array.push()</p> Signup and view all the answers

    What is the result of '5' + 3 in JavaScript?

    <p>'53'</p> Signup and view all the answers

    Which method is used to remove the last element from an array in JavaScript?

    <p>array.pop()</p> Signup and view all the answers

    What will be the result of the division 10 / '2' in JavaScript?

    <p>5</p> Signup and view all the answers

    What is the output of typeof null in JavaScript?

    <p>'object'</p> Signup and view all the answers

    Which comparison below would return false in JavaScript?

    <p>'5' === 5</p> Signup and view all the answers

    What happens when you use the 'delete' operator on a variable declared with var in JavaScript?

    <p>The variable becomes undefined</p> Signup and view all the answers

    What does the 'charAt' method in JavaScript do?

    <p>Returns the character at a specified index in the string</p> Signup and view all the answers

    How can you determine if a string contains a specific substring in JavaScript?

    <p>By using the 'indexOf' method</p> Signup and view all the answers

    What is the purpose of the 'instanceof' operator in JavaScript?

    <p>To check if a variable is an array</p> Signup and view all the answers

    What is the output of 1 + 2 + '3' in JavaScript?

    <p>'123'</p> Signup and view all the answers

    What is the purpose of the "toLocaleString" method in JavaScript?

    <p>To format a date according to the system's locale</p> Signup and view all the answers

    How do you convert a string to a date object in JavaScript?

    <p>new Date(string)</p> Signup and view all the answers

    What does the 'charAt' method do in JavaScript strings?

    <p>Selects the first character of the string</p> Signup and view all the answers

    What is the output of 3 > 2 > 1 in JavaScript?

    <p>true</p> Signup and view all the answers

    Study Notes

    JavaScript Fundamentals

    • The 'Promise' object in JavaScript is used to handle asynchronous operations, allowing you to write asynchronous code that is easier to read and maintain.

    Array Methods

    • The unshift() method is used to add a new element at the beginning of an array in JavaScript.
    • The push() method is used to add a new element to the end of an array in JavaScript.
    • The pop() method is used to remove the last element from an array in JavaScript.

    Storage

    • The 'localStorage' object in JavaScript is used to store data locally within the user's browser, allowing web applications to store and retrieve data even after the browser has been closed.

    APIs and Networking

    • The 'fetch' API in JavaScript is used to make HTTP requests and interact with servers, allowing web applications to retrieve and send data.

    Operators and Data Types

    • The 'typeof' operator in JavaScript is used to determine the data type of a variable or value, returning a string indicating the type of the operand.
    • The + operator in JavaScript performs string concatenation when one of the operands is a string.
    • The / operator in JavaScript performs arithmetic division, and converts the operands to numbers if necessary.

    Strings

    • The 'charAt' method in JavaScript is used to retrieve a character at a specific position in a string, with indexing starting from 0.
    • The indexOf() method in JavaScript is used to determine if a string contains a specific substring, returning the index of the substring if found, or -1 otherwise.

    Variables and Operators

    • The 'instanceof' operator in JavaScript is used to test whether an object is an instance of a particular constructor or prototype.
    • The delete operator in JavaScript is used to remove a property from an object, but has no effect on variables declared with var.

    Dates and Localization

    • The "toLocaleString" method in JavaScript is used to convert a date object to a string, using the browser's locale and language settings.
    • The Date constructor in JavaScript can be used to convert a string to a date object, by parsing the string in a browser-dependent manner.

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    Description

    Test your knowledge of JavaScript with these quiz questions covering topics like division by zero, the 'with' statement, and string manipulation methods. Choose the correct answers and see how well you know JavaScript!

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