Most Important JavaScript Interview Questions & Answers [2022]

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Most Important JavaScript Interview Questions & Answers [2022]



Content Of This Post ?
     
                                                             In this article, we covered sixteen JavaScript questions with answers.

  • What is JavaScript?
  • List some features of JavaScript.
  • Who developed JavaScript, and what was the first name given for it?
  • List a number of the benefits of JavaScript.
  • List a number of the negative aspects of JavaScript.
  • Explain the difference between JavaScript and JScript.
  • Name the types of functions.
  • What is an anonymous function in JavaScript?
  • In JavaScript, can an anonymous function be assigned to a variable?
  • In JavaScript, if we want to return the character from a specific index which
  • method can be used?
  • How to use an external JavaScript file?
  • Explain how to write HTML code dynamically using JavaScript language?
  • What is the real name of the JavaScript language?
  • What is the difference between == and ===?
  • Which are the pop-up boxes available in JavaScript?
  • How to create objects in JavaScript?


1. What is JavaScript?

                                JavaScript is a scripting language. It is different from the Java programming language.
It is an object-based, lightweight, cross-platform translated language. It is widely used for client-side validation. JavaScript translator is responsible for translating the"JavaScript code" for the web browser.

2. List some features of JavaScript.

Some of the features of JavaScript are
• Lightweight
• Interpreted programming language
• Good for the applications which are network-centric
• Complementary to Java
• Complementary to HTML
• Open-source
• Cross-platform

 

3. Who developed JavaScript, and what was the first name given for it?

                                            JavaScript was developed by Brendan Eich, and he was a Netscape programmer. 
Brendan Eich developed this scripting language in just ten days in the year 1995. 
JavaScript language was initially called Mocha; after that, it was called Live Script, and later, it is known as JavaScript.

4. List a number of the benefits of JavaScript.

Some of the advantages of JavaScript are:
• Server interaction is less
• Feedback to the visitors is immediate
• Interactivity is high
• Interfaces are richer

 

5. List a number of the negative aspects of JavaScript.

Some of the disadvantages of JavaScript are

• No support for multithreading.
• No support for multiprocessing.
• Writing and reading of files are not allowed.
• No support for networking applications.

 

6. Explain the difference between JavaScript and JScript.

                                   Netscape provided the JavaScript language. Then Microsoft changed the name and called it JScript to avoid the trademark issue. In other words, we can say JScript is similar to JavaScript, but Microsoft offers it.

7. Name the types of functions.

The types of functions are:

1. Named - This type of function contains a name at the time of definition. 

Example:

function display()
{
document.writeln("Named Function in invoked");
}
display();

 

2. Anonymous - These type of functions doesn't contain any name. They are
declared dynamically at runtime.

var display=function()
{
document.writeln("Anonymous Function");
}
display();

 

8. What is an anonymous function in JavaScript?

                                           Anonymous functions has no name. These anonymous functions are dynamically declared at run-time using the function operator. 

Example:

var display=function()
{
alert("The Anonymous Function is called");
}
display();

 

9. In JavaScript, can an anonymous function be assigned to a variable?

Yes, we are able to assign an anonymous function to a variable.

 

10. In JavaScript, if we want to return the character from a specific index which method can be used?

                      The string method charAt() is used to find out a character value present at the specified index. The index starts from 0 and goes to n-1, where n is the length of the string. The index value cannot be a negative, greater than or equal to the length of the string.

For example:-

var str="LEARNINGHOME99"; document.writeln(str.charAt(4));

11. How to use an external JavaScript file?

Place the below script tag inside the head tag.

      <script type="text/javascript" src="myjs.js"></script>

Is JavaScript language case sensitive?

     Yes, JavaScript is a case-sensitive language.

For example:

Var msg = "JavaScript is scripting language";
function display()
{
document.writeln(msg);
}
display();

12. Explain how to write HTML code dynamically using JavaScript language? 

The property innerHTML is used to write the HTML code using JavaScript 

dynamically.

Example:

 document.getElementById('mylocation').innerHTML="Text";

13. What is the real name of the JavaScript language?

The original name of the JavaScript was "Mocha", a name chosen by Marc Andreessen, founder of Netscape. In 1995, the name was changed to "LiveScript". In 1995, the name JavaScript was adopted.

14.What is the difference between == and ===?

The == operator checks equality only.

The === checks equality and data type, i.e., a value must be of the same type.

15. Which are the pop-up boxes available in JavaScript?

• Alert Box

• Confirm Box

• Prompt Box

16. How to create objects in JavaScript?

There are three ways to create an object in JavaScript.

1. By object literal

2. By creating an instance of Object

3. By Object Constructor

Example for creating an object using object literal:-

emp={id:102,name:"Rahul",salary:55000} 


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