JavaScript Essentials Quiz

1. What option would you specify when inserting code in a web page?

• script type=`text/javascript`
• script type=`text/css`
• script type=`text/html`
• script type=`text/json`

2. Is the following a valid variable definition? var 100apples

• No
• Sure
• Yes
• Maybe

3. Is the following a valid variable assignment var product cost = 3.45;

• No
• Certainly
• Yes
• Maybe

4. What is the ideal place to load the external JavaScript file in your HTML document?

• In a separate CSS file for styling purposes
• In the head section for immediate execution
• Towards the end of the body to increase the performance of the webpage
• Before the closing HTML tag for syntax validity

5. You want to create an alert. Select the correct one.

• alert(`he said `goodbye“)
• alert(`message`)
• alert(`hello there`)
• alert(`goodbye`)

6. To display whether a value is a number or not, ____ is used.

• isNaN
• checkNum
• numCheck
• isNumber

7. Select the statement that has correct JavaScript syntax.

• console.log<>text<>
• console.log(`text`)
• console.log(text)
• console.log{text}

8. What is true about variables in JavaScript?

• Variables are case sensitive
• Variables cannot be reassigned
• Variables must be declared with const
• Variables are immutable

9. JavaScript has to be called inside ________ tags.

• script
• body
• section
• header

10. Which of the following are not valid in JavaScript?

• `This would be an `error` example`
• `Hello, my name is `Sam“
• `My name is `Harry“
• `This is `JavaScript` usage`

11. What is the value of C? var a = 100; var b = `10`; var c = a + b;

• 110
• 1100
• 1000
• 10010

12. Which statement will return the value false?

• var result = (20 === `20`) && (50 < 30);
• var result = (10 == `10`) && (30 < 40);
• var result = (5 > 2) || (3 < 1);
• var result = (1 === 1) || (2 === 2);

13. What is the output for code A and B?

• 15,20
• 10,11
• 5,6
• 12,13

14. Multiple variables can be created and initialized in a single JavaScript statement.

• False
• Maybe
• Not sure
• True

15. ____ allows you to loop through a block of code as long as the specified condition is true.

• Repeat
• ForEach
• Loop
• While

16. ____ is used to exit a loop early.

• Break
• Terminate
• Stop
• Exit

17. What is the purpose of the `let` keyword in JavaScript?

• To declare block-scoped variables.
• To specify function parameters.
• To define constant values in the script.
• To create global variables only.

18. What is the purpose of the `const` keyword in JavaScript?

• To declare global variables.
• To declare mutable variables.
• To declare instance variables.
• To declare read-only variables.

19. How do you declare a variable in JavaScript?

• Using `assign` followed by the variable name.
• Defining with the `initialize` function.
• Setting variables using `declare`.
• Using the `var`, `let`, or `const` keyword.

20. What is the difference between `var` and `let` in JavaScript?

• `Var` is function-scoped, while `let` is block-scoped.
• `Let` cannot be reassigned, `var` can.
• `Let` allows hoisting, `var` does not.
• `Var` is always global-scoped.

21. What is the difference between `var` and `const` in JavaScript?

• `Var` and `const` are identical in functionality.
• `Var` allows hoisting, while `const` does not.
• `Var` can be reassigned, while `const` cannot be reassigned.
• `Var` is block-scoped, while `const` is function-scoped.

22. How do you concatenate strings in JavaScript?

• Using the `*` operator to combine strings.
• Using the `-` operator for strings.
• Using the `+` operator or the `concat` method.
• Using the `%` operator for string joining.

23. How do you access an array element in JavaScript?

• Using the length property, e.g., arr.length
• Using the index number, e.g., arr[0]
• Using the key name, e.g., arr(`key`)
• Using the array size, e.g., arr.size

24. What is the purpose of the `push` method in an array?

• To remove elements from the start of the array.
• To sort the elements in the array.
• To find the length of the array.
• To add elements to the end of the array.

25. What is the purpose of the `pop` method in an array?

• To add an element to the beginning of the array.
• To modify all elements in the array.
• To remove and return the last element of the array.
• To find the index of an element in the array.

26. How do you check if a value is a number in JavaScript?

• isNumber
• checkNumeric
• isValidNumber
• isNaN

27. How do you create a new object in JavaScript?

• Through the `create` function in the DOM.
• Using the `add` operator with literals.
• By assigning values to an existing variable.
• Using the `new` keyword and the object constructor.

28. What is an anonymous function in JavaScript?

• An anonymous function is a variable that holds a function.
• An anonymous function is a function without parameters.
• An anonymous function is a function without a name.
• An anonymous function is a function called by name.

29. What is a method in JavaScript?

• A method is a condition that checks values.
• A method is a function contained within an object.
• A method is a loop that repeats actions.
• A method is a variable that stores data.

30. How do you call a function in JavaScript?

• Using the function name followed by parentheses with arguments if any.
• Calling with an equal sign and value.
• Assigning to the function variable directly.
• Using the function without parentheses at all.