1 JavaScript Data Types Quiz
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1 JavaScript Data Types Quiz

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Questions and Answers

Which of the following correctly represents the string type in JavaScript?

  • Backticks: 'Hello'. (correct)
  • Single quotes: 'Hello'. (correct)
  • Floating quotes: 'Hello'.
  • Double quotes: 'Hello'. (correct)
  • What does the value 'null' represent in JavaScript?

  • A boolean false value.
  • A special value representing 'nothing'. (correct)
  • An undeclared variable.
  • An empty string.
  • What indicates that a variable has not been assigned a value?

  • null
  • undefined (correct)
  • NaN
  • 0
  • What will the expression '11 > 7' return in JavaScript?

    <p>true</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 statement regarding the number type in JavaScript is true?

    <p>It can represent both integer and floating-point numbers.</p> Signup and view all the answers

    Which of the following values is considered NaN (Not a Number) in JavaScript?

    <p>alert('not a number' / 2 + 5)</p> Signup and view all the answers

    Which statement about booleans in JavaScript is correct?

    <p>They can only hold values true or false.</p> Signup and view all the answers

    What is a primary characteristic that differentiates JavaScript from Java?

    <p>JavaScript is a scripting language created for web development.</p> Signup and view all the answers

    Which ECMAScript version was abandoned?

    <p>ES4</p> Signup and view all the answers

    How can JavaScript programs be embedded in an HTML document?

    <p>Using the script tag anywhere within the HTML document.</p> Signup and view all the answers

    What is the role of the Math object in JavaScript?

    <p>It provides mathematical constants and functions.</p> Signup and view all the answers

    Which of the following statements about JavaScript syntax is correct?

    <p>Statements can be separated with semicolons.</p> Signup and view all the answers

    What is a primary use of the JavaScript DOM?

    <p>To manipulate and interact with HTML content.</p> Signup and view all the answers

    Which of the following best describes the use of the 'alert' function in JavaScript?

    <p>It displays a message in a dialog box and pauses execution.</p> Signup and view all the answers

    In what scenario would you typically use local storage in JavaScript?

    <p>To remember user preferences on the client side.</p> Signup and view all the answers

    Which statement best describes the purpose of a variable in JavaScript?

    <p>A variable is a named storage for data.</p> Signup and view all the answers

    Which declaration is considered correct for multiple variables in one line?

    <p>let user = 'John', age = 25;</p> Signup and view all the answers

    What is the purpose of the const keyword in variable declaration?

    <p>To declare a variable that cannot be changed.</p> Signup and view all the answers

    Which of the following is NOT a valid variable name in JavaScript?

    <p>1stVariable</p> Signup and view all the answers

    What will be the result of the following operation: let a = 10; a += 5;?

    <p>15</p> Signup and view all the answers

    What does the expression '8 % 3' evaluate to?

    <p>2</p> Signup and view all the answers

    Which of the following describes the camelCase naming convention in JavaScript variables?

    <p>The first word is in lowercase followed by words starting with capital letters.</p> Signup and view all the answers

    In JavaScript, what does the command 'alert(5 % 2)' produce?

    <p>1</p> Signup and view all the answers

    What does the expression 'a % b' return?

    <p>The remainder of the integer division of a by b.</p> Signup and view all the answers

    Which operation is NOT a unary operation?

    <p>a + b</p> Signup and view all the answers

    Which of the following methods returns a pseudorandom number?

    <p>Math.random()</p> Signup and view all the answers

    In prefix notation, how would you increment the variable 'a' by 1?

    <p>++a</p> Signup and view all the answers

    Which statement is TRUE about JavaScript primitive data types?

    <p>Boolean is a primitive data type.</p> Signup and view all the answers

    Which operation is an example of a binary operation?

    <p>a &amp;&amp; b</p> Signup and view all the answers

    How can you retrieve the absolute value of a number 'x' in JavaScript?

    <p>Math.abs(x)</p> Signup and view all the answers

    What will the following code output: console.log('a = ' + 5); ?

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

    Study Notes

    JavaScript Data Types

    • JavaScript has three types of quotes:
      • Double quotes: "Hello"
      • Single quotes: 'Hello'
      • Backticks: Hello

    Number

    • Number type represents both integers and floating point numbers
    • Special numeric values include:
      • Infinity: alert( 1 / 0 )
      • NaN (Not a Number): alert( "not a number" / 2 + 5 )

    Boolean

    • Represents logical type with two values: true and false
    • Used for yes/no values, true represents "yes" and false "no"
    • true is assigned to nameFieldChecked when the field is checked
    • false is assigned to ageFieldChecked when the field is not checked

    Null

    • null is a special value representing "nothing", "empty" or "value unknown"

    Undefined

    • undefined indicates a value has not been assigned
    • If a variable is declared but not assigned, its value will be undefined

    typeof Operator

    • The typeof operator returns the type of the argument
    • Two forms of syntax:
      • As an operator: typeof x
      • In parentheses: (typeof x)

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    Related Documents

    JavaScript Fundamentals PDF

    Description

    Test your knowledge of JavaScript data types including strings, numbers, booleans, null, and undefined. This quiz will help reinforce your understanding of how these data types work and their specific uses in JavaScript programming.

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