JavaScript Multiple-Choice Questions (MCQs)

JavaScript, often abbreviated JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS.

JavaScript MCQs: This section contains JavaScript Multiple-Choice Questions with Answers. These JavaScript MCQs are written for beginners as well as advanced, practice these MCQs to enhance and test the knowledge of JavaScript.

List of JavaScript MCQs

1. JavaScript is the programming language of the _____.

  1. Desktop
  2. Mobile
  3. Web
  4. Server

Answer: C) Web

Explanation:

JavaScript is the programming language of the Web.

Discuss this Question


2. Which type of JavaScript language is _____?

  1. Object-oriented
  2. Object-based
  3. Functional programming
  4. All of the above

Answer: B) Object-based

Explanation:

JavaScript is an object-oriented based programming language.

Discuss this Question


3. Which of the following statement(s) is true about the JavaScript?

  1. It is a scripting language used to make the website interactive
  2. It is an advanced version of Java for Desktop and Mobile application development
  3. It is a markup language of Java to develop the webpages
  4. All of the above

Answer: A) It is a scripting language used to make the website interactive

Explanation:

The correct statement about the JavaScript programming language is "It is a scripting language used to make the website interactive".

Discuss this Question


4. In which HTML element, we put the JavaScript code?

  1. <javascript>...</javascript>
  2. <js>...</js>
  3. <script>...</script>
  4. <css>...</css>

Answer: C) <script>...</script>

Explanation:

The JavaScript code is written inside the <script>...</script> tag/element.

Discuss this Question


5. JavaScript code can be written in ____.

  1. JavaScript file (.js file)
  2. HTML document directly
  3. JavaScript file and in HTML document directly
  4. In style sheets (.css file)

Answer: C) JavaScript file and in HTML document directly

Explanation:

JavaScript code can be written in the JavaScript file and in HTML document directly.

Discuss this Question


Advertisement

6. Which symbol is used separate JavaScript statements?

  1. Comma (,)
  2. Colon (:)
  3. Hyphen (_)
  4. Semicolon (;)

Answer: D) Semicolon (;)

Explanation:

The semicolon (;) is used to separate the JavaScript statements.

Discuss this Question


7. JavaScript ignores?

  1. newlines
  2. tabs
  3. spaces
  4. All of the above

Answer: D) All of the above

Explanation:

JavaScript ignores spaces, tabs, and newlines written in the code, we can use them for the alignment and separate the sections to give a perfect look at our code.

Discuss this Question


8. Which is the correct syntax to call an external JavaScript file in the current HTML document?

  1. <script src="jsfile.js"></script>
  2. <script href=" jsfile.js"></script>
  3. <import src=" jsfile.js"></import>
  4. <script link=" jsfile.js"></script>

Answer: A) <script src="jsfile.js"></script>

Explanation:

The correct syntax to call an external JavaScript file in the current HTML document is:

<script src="jsfile.js"></script>

Discuss this Question


9. Which JavaScript method is used to access an HTML element by id?

  1. getElementById()
  2. getElement(id)
  3. getElementById(id)
  4. elementById(id)

Answer: C) getElementById(id)

Explanation:

The JavaScript method document.getElementById(id) is used to access an HTML document by id.

Discuss this Question


10. Which property is used to define the HTML content to an HTML element with a specific id?

  1. innerText
  2. innerContent
  3. elementText
  4. innerHTML

Answer: D) innerHTML

Explanation:

The innerHTML is the property that defined HTML content.

Example:

document.getElementById("notif").innerHTML = "New course launched";

Discuss this Question


Advertisement

11. Which JavaScript method is used to write HTML output?

  1. document.write()
  2. document.output()
  3. console.log()
  4. document.writeHTML()

Answer: A) document.write()

Explanation:

The JavaScript method document.write() defines the HTML output.

Discuss this Question


12. Which JavaScript method is used to write on browser's console?

  1. console.write()
  2. console.output()
  3. console.log()
  4. console.writeHTML()

Answer: C) console.log()

Explanation:

The JavaScript method console.log() is used to write on browser's console.

Discuss this Question


13. Which JavaScript method is used to write into an alert box?

  1. window.alertHTML()
  2. window.alert()
  3. window.alertBox()
  4. window.alertContent()

Answer: B) window.alert()

Explanation:

The JavaScript method window.alert() is used to write into an alert box.

Discuss this Question


14. Which is the correct JavaScript statement to display "Hello Boss!" into an alert box?

  1. alert("Hello Boss!");
  2. alert('Hello Boss!');
  3. alert(Text:'Hello Boss!');
  4. Both A. and B.

Answer: D) Both A. and B.

Explanation:

The both of statement are correct to display "Hello Boss!" into an alert box:

window.alert("Hello Boss!");
window.alert('Hello Boss!');

Discuss this Question


15. Which is the correct JavaScript statement to print the addition of two numbers 10 and 20 in a paragraph whose id is 'result'?

  1. getElementById("result").innerHTML = 10+20;
  2. getElementById("result").innerHTML = "10+20";
  3. getElementById("#result").innerHTML = 10+20;
  4. All of the above

Answer: A) getElementById("result").innerHTML = 10+20;

Explanation:

The correct JavaScript statement to print the addition of two numbers 10 and 2o in a paragraph whose id is "result" is:

document.getElementById("result").innerHTML = 10+20;

Discuss this Question


Advertisement

16. What is the use of this JavaScript statement?

<button onclick="window.print()">Submit</button>
  1. It will write "Submit" on the current Window
  2. It will print the content of the current page
  3. It will write the content of the current page in the browser’s console
  4. None of the above

Answer: B) It will print the content of the current page

Explanation:

The window.print() method prints the content of the current page.

Discuss this Question


17. In JavaScript, single line comment begins with ___.

  1. #
  2. /*
  3. $
  4. //

Answer: D) //

Explanation:

In JavaScript, single line comment begins with //.

Discuss this Question


18. In JavaScript, multi-line comments start with __ and end with ___.

  1. /* and */
  2. <!—and -->
  3. ## and ##
  4. // and //

Answer: A) /* and */

Explanation:

In JavaScript, multi-line comments start with /* and end with */.

Discuss this Question


19. Which JavaScript keyword is used to declare a variable?

  1. Var
  2. var
  3. Let
  4. All of the above

Answer: B) var

Explanation:

The var keyword defines a variable in JavaScript.

Discuss this Question


20. How many keywords are there in JavaScript to declare variables or constants?

  1. 1
  2. 2
  3. 3
  4. 4

Answer: C) 3

Explanation:

There are 3 ways / keywords to declare variables or constants, those are:

  • var
  • let
  • const

Discuss this Question


Advertisement

21. What is the main difference between var and let keywords in JavaScript?

  1. var defines a variable while let defines a constant
  2. var defined function scoped variable while let define block scoped variable
  3. The value of a variable declared with var can be changed while the value of a variable declared with let cannot be changed
  4. All of the above

Answer: B) var defined function scoped variable while let define block scoped variable

Explanation:

The var and let keywords are both used for variable declaration in JavaScript. But, the main difference between them is that var defines function scoped variable while let defines block-scoped variable.

Discuss this Question


22. The const keyword is used to define a ______.

  1. Function scopes variable
  2. Block scoped variable
  3. Constant
  4. Constant with no initial value

Answer: C) Constant

Explanation:

The const keyword is used to define a constant.

Discuss this Question


23. Which is the correct syntax to declare a constant in JavaScript?

  1. const constant_name;
  2. constant_name const;
  3. constant_name const = value;
  4. const constant_name = value;

Answer: D) const constant_name = value;

Explanation:

The correct syntax to declare a constant is:

const constant_name = value;

Example:

const PI = 3.14; 

Discuss this Question


24. What will be the value of VALUE?

<script>
	const VALUE = 10;
	VALUE = 20;
</script>
  1. 10
  2. 20
  3. ValueError
  4. TypeError

Answer: D) TypeError

Explanation:

We cannot change the value of a constant, thus the above code will generate a TypeError – "TypeError: Assignment to constant variable"

Discuss this Question


25. What is the default value of an uninitialized variable?

  1. 0
  2. undefined
  3. null
  4. NaN

Answer: B) undefined

Explanation:

The default value of an unfinalized variable is undefined.

Discuss this Question


26. What is the output of the following JavaScript code?

<script>
	var a;
	document.getElementById("demo").innerHTML = a+1;
</script>
  1. 0
  2. undefined
  3. 1
  4. NaN

Answer: D) NaN

Explanation:

The output of the above JavaScript code is: NaN

Discuss this Question


27. Can be redeclare a variable that is declared with var keyword?

  1. Yes
  2. No

Answer: A) Yes

Explanation:

Yes, we can redeclare variable that is declared with var keyword.

Discuss this Question


28. What is the output of the following JavaScript code?

<script>
	var name = "Alex" + " " + "Alvin";
	document.getElementById("demo").innerHTML = name;
</script>
  1. Alex Alvin
  2. AlexAlvin
  3. TypeError
  4. ValueError

Answer: A) Alex Alvin

Explanation:

The output of the above JavaScript code is: "Alex Alvin"

Discuss this Question


29. What is the output of the following JavaScript code?

<script>
	var a = 10 + 20 + "5";
	document.getElementById("demo").innerHTML = a;
</script>
  1. 35
  2. 305
  3. TypeError
  4. ValueError

Answer: B) 305

Explanation:

The output of the above JavaScript code is: 305

Discuss this Question


30. Can be redeclare a variable that is declared with let keyword?

  1. Yes
  2. No

Answer: B) No

Explanation:

No, we cannot redeclare variable that is declared with let keyword.

Discuss this Question


Advertisement

31. What is the output of the following JavaScript code (let example)?

<script>
	let a = 10;
	let a = 0;
</script>
  1. 10
  2. 0
  3. SyntaxError
  4. TypeError

Answer: C) SyntaxError

Explanation:

The output of the above JavaScript code is: "SyntaxError: 'a' has already been declared".

Discuss this Question


32. Which is the exponentiation operator in JavaScript?

  1. exp()
  2. ^
  3. **
  4. pow

Answer: C) **

Explanation:

The exponentiation operator in JavaScript is ** which is used to calculate the result of first operand's to the power of the second operators i.e., x**y = x to the power of y (xy).

Discuss this Question


33. Does JavaScript support increment (++) and decrements (--) Operators?

  1. Yes
  2. No

Answer: A) Yes

Explanation:

Yes, JavaScript supports increment (++) and decrements (--) operators.

Example:

<script>
	var x = 5;
	document.getElementById("test").innerHTML = ++x;
</script>

Discuss this Question


34. What will be the output of the following JavaScript code?

<script>
	var x = 5;
	document.getElementById("demo").innerHTML = x--;
</script>
  1. 5
  2. 4
  3. TypeError
  4. ValueError

Answer: B) 4

Explanation:

The output of the above statement will be 5.

In the above statement, we used post-decrement (x--). Post-decrement decreases the value by 1 after evaluating the current statement.

Discuss this Question


35. What will be the output of the following JavaScript code?

<script>
	var x = 10 + 20 * 5;
	document.getElementById("tes").innerHTML = x;
</script>
  1. 110
  2. 150
  3. TypeError
  4. ValueError

Answer: A) 110

Explanation:

The output of the above statement will be 110.

In the above code, the expression is 10 + 20 * 5. The precedence of multiplication operator (*) is higher than the addition operator (+). This 20 *5 will evaluate first.

Discuss this Question


36. What will be the output of the following JavaScript code?

<script>
	var x = (10 + 20) * 5;
	document.getElementById("tes").innerHTML = x;
</script>
  1. 110
  2. 150
  3. TypeError
  4. ValueError

Answer: B) 150

Explanation:

The output of the above statement will be 150.

In the above code, the expression is (10 + 20) * 5. The precedence of () are higher than any other operators This (10 + 20) will evaluate first.

Discuss this Question


37. JavaScript types are _____.

  1. Static
  2. Dynamic

Answer: B) Dynamic

Explanation:

JavaScript types are dynamic, which means the same variable can be used to store the different types of values.

Discuss this Question


38. JavaScript arrays are written with _____.

  1. round brackets ()
  2. curly brackets {}
  3. double quotes ""
  4. square brackets []

Answer: D) square brackets []

Explanation:

JavaScript arrays are written with square brackets [].

Discuss this Question


39. JavaScript objects are written with _____.

  1. round brackets ()
  2. curly brackets {}
  3. double quotes ""
  4. square brackets []

Answer: B) curly brackets {}

Explanation:

JavaScript objects are written with curly brackets {}.

Discuss this Question


40. Which JavaScript operator is used to determine the type of a variable?

  1. typeof
  2. TypeOf
  3. typeOf
  4. sizeof

Answer: A) typeof

Explanation:

The typeof operator is used to determine the type of a variable.

Discuss this Question


41. Which is the correct syntax of JavaScript typeof operator?

  1. typeof variable/value
  2. typeof(variable/value)
  3. Both A. and B.
  4. None of the above

Answer: C) Both A. and B.

Explanation:

Both of the syntaxes can be used for JavaScript typeof operator.

Discuss this Question


42. What will be the output of the following JavaScript code?

<script>
	var x = 12.34;
	document.getElementById("test").innerHTML = typeof(x);
</script>
  1. int
  2. float
  3. long
  4. number

Answer: D) number

Explanation:

The output of the following JavaScript code is number.

Discuss this Question


43. Which keyword is used to define a JavaScript function?

  1. module
  2. fun
  3. func
  4. function

Answer: D) function

Explanation:

The function keyword is used to define the JavaScript function.

Discuss this Question


44. Which is the correct syntax for the function definition?

  1. return_type function function_name(parameter1, parameter2, ...) { /*Function's body*/ }
  2. function function_name(parameter1, parameter2, ...) { /*Function's body*/ }
  3. return_type function_name(parameter1, parameter2, ...) { /*Function's body*/ }
  4. function function_name(parameter1, parameter2, ...) as return_type { /*Function's body*/ }

Answer: B) function function_name(parameter1, parameter2, ...) { /*Function's body*/ }

Explanation:

The function definition syntax is:

function function_name(parameter1, parameter2, ...)
{ 
	/*Function's body*/ 
}

Discuss this Question


45. What will be the output of the following JavaScript code?

<script>
	function addition(a, b) {
		return a+b;
	}
	document.getElementById("test").innerHTML = addition;
</script>
  1. SyntaxError
  2. ValueError
  3. 0
  4. function addition(a, b) { return a+b; }

Answer: D) function addition(a, b) { return a+b; }

Explanation:

Calling of a function without () will return the function definition i.e., function object instead of the result.

Discuss this Question


46. Can we use a function as a variable value?

  1. Yes
  2. No

Answer: A) Yes

Explanation:

Yes, a function can be used as a variable value.

Discuss this Question


47. In JavaScript a variable contains one value while an object may contain ___.

  1. One value
  2. Two values
  3. Three values
  4. Many values

Answer: D) Many values

Explanation:

In JavaScript a variable contains one value while an object may contain many values.

Discuss this Question


48. Which is the correct syntax to access an object property in JavaScript?

  1. objectName:propertyName
  2. propertyName
  3. objectName["propertyName"]
  4. Both B. and C.

Answer: D) Both B. and C.

Explanation:

The properties of an object can we accessed using either objectName.propertyName or objectName["propertyName"].

Discuss this Question


49. Which property is used to get the length of a string in JavaScript?

  1. strlen
  2. len
  3. length
  4. Length

Answer: C) length

Explanation:

The length property is used to get the length of a string in JavaScript.

Discuss this Question


50. What will be the output of the following JavaScript code?

<script>
	let str = "IncludeHelp";
	document.getElementById("test").innerHTML = str.length;
</script>
  1. 11
  2. 12
  3. ValueError
  4. SyntaxError

Answer: A) 11

Explanation:

The output of the above statement will be the length of the string. That is 11.

Discuss this Question


51. Which character is used to break up a code line within a text string in JavaScript?

  1. Single quote (')
  2. Single backslash (\)
  3. Double quote (")
  4. Tipple single quote (''')

Answer: B) Single backslash (\)

Explanation:

The Single backslash (\) is used to break up a code line within a text string in JavaScript.

Example:

document.getElementById("test").innerHTML = "Hello \
IncludeHelp!";

Discuss this Question


52. Will the following JavaScript code work?

<script>
	document.getElementById("test").innerHTML = \
	"Hello, IncludeHelp!";
</script>
  1. Yes
  2. No

Answer: B) No

Explanation:

No, the above code will not work. Because, we cannot breakup a JavaScript code line with single backslash (\).

Discuss this Question


53. Which is the correct JavaScript statement to define string as object?

  1. var s = new String("IncludeHelp!");
  2. var s = String("IncludeHelp!");
  3. var s = "IncludeHelp!"
  4. All of the above

Answer: A) var s = new String("IncludeHelp!");

Explanation:

The strings can also be defined as an object using the new keyword. The correct JavaScript statement to define a string as an object is:

var s = new String("IncludeHelp!");

Discuss this Question


54. What will be the output of the following JavaScript code?

<script>
	let str1 = new String("IncludeHelp!");
	let str2 = new String("IncludeHelp!");
	document.getElementById("test").innerHTML = (str1==str2);
</script>
  1. true
  2. false
  3. True
  4. False

Answer: B) false

Explanation:

In the above code, str1 and str2 are the objects. And. In the JavaScript, comparison of two objects returns false.

Discuss this Question


55. Which is/are the valid JavaScript method(s) to extract string parts?

  1. slice(start, end)
  2. substring(start, end)
  3. substr(start, length)
  4. All of the above

Answer: D) All of the above

Explanation:

The all of the above JavaScript methods can be used to extract string parts.

Discuss this Question


56. What will be the output of the following JavaScript code?

<script>
    let x = "Hello, IncludeHelp!";
    document.getElementById("test").innerHTML = x.slice(-13,-1);
</script>
  1. IncludeHelp!
  2. IncludeHelp
  3. ValueError
  4. Hello,

Answer: B) IncludeHelp

Explanation:

The negative value counts from the end of the string. Thus, the output will be "IncludeHelp".

Discuss this Question


57. In JavaScript, the string template literals use ____ rather than the quotes ("") to define a string?

  1. Single quotes ('')
  2. Backslash with single quote (\’'\')
  3. Backslashes (\\)
  4. Back-ticks (``)

Answer: D) Back-ticks (``)

Explanation:

In JavaScript, the string template literals use back-ticks (``) rather than the quotes ("") to define a string.

Discuss this Question


58. Does the following JavaScript variable definition is correct?

let x = `I'm "David!"`;
  1. Yes
  2. No

Answer: A) Yes

Explanation:

The JavaScript variable definition statement is true. Because, with the JavaScript template literals, we can use both single and double quotes inside a string.

Discuss this Question


59. Which JavaScript method is used to get a number as a string?

  1. toString()
  2. intToString()
  3. parseInteger()
  4. All of the above

Answer: A) toString()

Explanation:

The JavaScript method toString() is used to get a number as a string.

Discuss this Question


60. What will be the output of the following JavaScript code?

<script>
    const myArray = ['h', 'e', 'l', 'l', 'o'];
    document.write(myArray[0]);
    document.write(myArray[1]);
</script>
  1. he
  2. undefinedh
  3. ValueError
  4. TypeError

Answer: A) he

Explanation:

In JavaScript, the array indexing starts with 0. Thus, the above statement with print "h" and "e".

Discuss this Question


61. What will be the output of the following JavaScript code?

<script>
    let cars = ['Honda', 'Hyundai'];
    cars.push('Mahindra');
    document.write(typeof cars + " " + cars);
</script>
  1. array Honda,Hyundai,Mahindra
  2. string Honda,Hyundai,Mahindra
  3. object Honda,Hyundai,Mahindra
  4. object "Honda", "Hyundai", "Mahindra"

Answer: C) object "Honda", "Hyundai", "Mahindra"

Explanation:

The push() method pushes an element at the end of the array. And, typeof returns the type of the object. Here, cars is an array.

Discuss this Question


62. What will be the output of the following JavaScript code?

<script>
    let cars1 = ['Honda', 'Hyundai'];
    let cars2 = cars1;
    
    cars1.push('Mahinda');
    
    document.write(cars1 + "---" + cars2);
</script>
  1. Honda,Hyundai,Mahinda---Honda,Hyundai
  2. Honda,Hyundai,Mahinda---Honda,Hyundai,Mahinda
  3. Honda,Hyundai ---Honda,Hyundai
  4. [Honda,Hyundai,Mahinda]---[Honda,Hyundai,Mahinda]

Answer: B) Honda,Hyundai,Mahinda---Honda,Hyundai,Mahinda

Explanation:

In the JavaScript, the arrays are objects, and the array elements are stored by reference. Hence, when an array value is copied, any change in the copied array will also reflect in the original array. Thus, the values of cars1 and cars2 are the same.

Discuss this Question


63. What will be the output of the following JavaScript code?

<script>  
	var msgs=new Array("Hello","Hey","Morning!");  

	for (i=0;i<msgs.length;i++){  
		document.write(msgs[i] + " | ");  
	}
</script>
  1. Hello | Hey | Morning! |
  2. Hello | Hey |
  3. ValueError
  4. TypeError

Answer: A) Hello | Hey | Morning! |

Explanation:

In the above JavaScript code, the array is declared using the new operator and all elements are printing using the loop. Thus, the output would be "Hello | Hey | Morning! |".

Discuss this Question


64. What will be the output of the following JavaScript code?

<script>
	var values = [10, 20, 30, 40];
	
	var result = values.reduceRight(function(x,y){
		return (x + y);
	});
	
	document.write("Result: " + result);
</script>
  1. Result: 40
  2. Result: 70
  3. Result: 90
  4. Result: 100

Answer: D) Result: 100

Explanation:

In the above JavaScript code, we used the reduceRight() method which is used to reduce the given array elements into a single value by executing a reducer function. The reducer() function is applied against the accumulator and reduces all the elements from right to left. Thus, the output would be "Result: 100".

Discuss this Question


65. What will be the output of the following JavaScript code?

<script>
	var cars = ["Honda","Hyundai","Mahindra"];
	
	var result = cars.shift();
	
	document.writeln("Result: ", cars);
</script>
  1. Result: Honda,Hyundai,Mahindra
  2. Result: Honda
  3. Result: Hyundai,Mahindra
  4. Result: Honda,Mahindra

Answer: C) Result: Hyundai,Mahindra

Explanation:

In the above JavaScript code, we used the shift() method which is used to remove the first element of the given array and return that element. This method changes the length of the original array. Thus, the output would be "Result: Hyundai,Mahindra".

Discuss this Question


66. What will be the output of the following JavaScript code?

<script>
	var cars = ["Honda","Hyundai","Mahindra"];

	var result = cars.unshift("Toyota", "Tata");

	document.writeln("[", result, "] ", cars);
</script>
  1. [5] Toyota,Tata,Honda,Hyundai,Mahindra
  2. [5]Honda,Hyundai,Mahindra,Toyota,Tata
  3. [2] Toyota,Tata
  4. [5] Honda,Hyundai,Toyota,Tata,Mahindra

Answer: A) [5] Toyota,Tata,Honda,Hyundai,Mahindra

Explanation:

In the above JavaScript code, we used unshift() method which is used to add one or more elements in the beginning of the given array and returns the updated array. This method changes the length of the original array. Thus, the output would be "[5] Toyota,Tata,Honda,Hyundai,Mahindra".

Discuss this Question


67. Which JavaScript method is used to call a function (a callback function) once for each array element?

  1. for()
  2. traverse()
  3. forEach()
  4. foreach()

Answer: C) forEach()

Explanation:

The JavaScript method forEach() is used to call a function (a callback function) once for each array element.

Discuss this Question


68. What will be the output of the following JavaScript code?

<script>
	const arr = [10, 20, 30];
	let result = 0;
	
	arr.forEach(myFunction);
	
	document.write("Result: " , result)
	function myFunction(value, index, array) {
	  result += value; 
	}
</script>
  1. Result: 60
  2. Result: 102030
  3. Result: 10,20,30
  4. ValueError

Answer: A) Result: 60

Explanation:

In the above JavaScript code, we used the forEach() method which is used to call a function (a callback function) once for each array element, and in the callback function, we are adding the elements of the array. Thus, the output would be "Result: 60".

Discuss this Question


69. What will be the output of the following JavaScript code?

<script>
	const values = [10, 20, 30];
	const result = values.map(myFunction);

	document.write("Result: ", result);

	function myFunction(value, index, array) {
	  return value * value;
	}
</script>
  1. Result: 10,20,30
  2. Result: 10*10,20*20,30*30
  3. Result: 100,400,900
  4. ValueError

Answer: C) Result: 100,400,900

Explanation:

In the above JavaScript code, we used the map() method which is used to create a new array by performing a function on each array element, and in the myFunction() we are multiplying the elements with the same value. Thus, the output would be "Result: 100,400,900".

Discuss this Question


70. Which JavaScript method is used to create a new array with array elements that passes a test?

  1. forEach()
  2. map()
  3. forMap()
  4. filter()

Answer: D) filter()

Explanation:

The JavaScript method filter() is used to create a new array with array elements that pass a test.

Discuss this Question


71. Which JavaScript object works with the dates?

  1. Date
  2. DateTime
  3. date
  4. dateTime

Answer: A) Date

Explanation:

The JavaScript Date object works with the dates.

Discuss this Question


72. Which JavaScript statement(s) is correct to create Date object(s) with new Date() constructor?

  1. new Date()
  2. new Date(year, month, day, hours, minutes, seconds, milliseconds)
  3. new Date(milliseconds)
  4. new Date(date string)
  5. All of the above

Answer: E) All of the above

Explanation:

All of the above statements are correct to create Date objects with new Date() constructor.

Discuss this Question


73. What will be the output of the following JavaScript code?

<script>
	const curr = new Date();
	document.write(curr);
</script>
  1. Tue Dec 21 2021 13:04:36 GMT+0530
  2. Tue Dec 21 2021 13:04:36 (India Standard Time)
  3. Tue Dec 21 2021 13:04:36::00::01 GMT+0530 (India Standard Time)
  4. Tue Dec 21 2021 13:04:36 GMT+0530 (India Standard Time)

Answer: D) Tue Dec 21 2021 13:04:36 GMT+0530 (India Standard Time)

Explanation:

The above JavaScript code will print the current date & time in the format of Tue Dec 21 2021 13:04:36 GMT+0530 (India Standard Time).

Discuss this Question


74. Which JavaScript method is used to convert a date to a UTC string (a date display standard)?

  1. toUTCString()
  2. toUtcString()
  3. utcString()
  4. toutcstring()

Answer: A) toUTCString()

Explanation:

The JavaScript method toUTCString() is used to convert a date to a UTC string (a date display standard).

Discuss this Question


75. The internal clock in JavaScript counts from midnight _____.

  1. January 1, 1972
  2. January 1, 1947
  3. January 1, 1980
  4. January 1, 1970

Answer: D) January 1, 1970

Explanation:

The internal clock in JavaScript counts from midnight January 1, 1970.

Discuss this Question


76. What does the Date object's method getTime() return?

  1. Date in DD-MM-YYYY format
  2. Date in DD MON YYYY format
  3. Date in MON, DD YYYY format
  4. Number of milliseconds since January 1, 1970

Answer: D) Number of milliseconds since January 1, 1970

Explanation:

The Date object's method getTime() returns the number of milliseconds since January 1, 1970.

Discuss this Question


77. Which method is used to get the year of a date as a four-digit number?

  1. getYear()
  2. fullYear()
  3. getFullYear()
  4. getfullyear()

Answer: C) getFullYear()

Explanation:

The getFullYear() method is used to get the year of a date as a four-digit number.

Discuss this Question


78. What will be the output of the following JavaScript code?

<script>
	document.write(Math.round(107.5))
</script>
  1. 107.5
  2. 107
  3. 108
  4. 107.00

Answer: C) 108

Explanation:

The Math.round(x) returns the value of x rounded to its nearest integer. Thus, the output would be 108.

Discuss this Question


79. What will be the output of the following JavaScript code?

<script>
try{
	const cars = {  
		company: 'Honda'
	};  

	delete cars.company;
	document.write(cars.company);  
}
catch (err){
	document.write(err.message);
}
</script>
  1. undefined
  2. Honda
  3. ValueError
  4. TypeError

Answer: A) undefined

Explanation:

In the above JavaScript code, the statement delete cars.company; will delete the property. Thus, the output would be "undefined".

Discuss this Question


80. What will be the output of the following JavaScript code?

<script>
try{
    const cars = {  
        company: 'Honda'
    };  
    
    Object.seal(cars);
    delete cars.company;
    document.write(cars.company);  
}
catch (err){
    document.write(err.message);
}
</script>
  1. undefined
  2. Honda
  3. ValueError
  4. TypeError

Answer: B) Honda

Explanation:

In the above JavaScript code, we have sealed the object and the seal property does not allow the object to be deleted. Hence, the property company will not be deleted.

Discuss this Question


81. What will be the output of the following JavaScript code?

<script>
    let x = "10";
    let y = + x;
    
    document.write(typeof y);
</script>
  1. string
  2. object
  3. undefined
  4. number

Answer: D) number

Explanation:

In JavaScript, the unary + operator can be used to convert a variable to a number. Hence, the statement let y = + x; will convert variable to number.

Discuss this Question


82. What will be the output of the following JavaScript code?

<script>
    let x = 10;
    
    document.write(typeof x, " , ", typeof String(x));
</script>
  1. number , string
  2. number , number
  3. object , string
  4. object , object

Answer: A) number , string

Explanation:

In the above JavaScript code, we are using the String() method which is a global method to convert numbers to string. Thus, the statement typeof String(x) will return string.

Discuss this Question


83. What will be the output of the following JavaScript code?

<script>
    let x = 10;
    
    document.write(x, " , ", toString(x));
</script>
  1. 10 , 10
  2. 10 , undefined
  3. 10 , [object Undefined]
  4. None of the above

Answer: C) 10 , [object Undefined]

Explanation:

In the above JavaScript code, the statement toString(x) will not convert number to string because toString() is not a global method, it is a Number method and the correct way is to call this function is x.toString().

Discuss this Question



ADVERTISEMENT
ADVERTISEMENT




Comments and Discussions!




Languages: » C » C++ » C++ STL » Java » Data Structure » C#.Net » Android » Kotlin » SQL
Web Technologies: » PHP » Python » JavaScript » CSS » Ajax » Node.js » Web programming/HTML
Solved programs: » C » C++ » DS » Java » C#
Aptitude que. & ans.: » C » C++ » Java » DBMS
Interview que. & ans.: » C » Embedded C » Java » SEO » HR
CS Subjects: » CS Basics » O.S. » Networks » DBMS » Embedded Systems » Cloud Computing
» Machine learning » CS Organizations » Linux » DOS
More: » Articles » Puzzles » News/Updates

© https://www.includehelp.com some rights reserved.