Top 10 JavaScript Interview Questions & Answers

Sometimes users and beginners couldn`t compare JavaScript and Java. Formally, JavaScript differ from Java even though they have resembling names. If you want to be a successful developer with high salary and have professional skills, you must know everything about JavaScript. If you are not interested in this topic, you can stop reading, because now we will discuss top 10 JavaScript interview questions.

  1. Question: what JavaScript is? We will start with the most common question. As we said before, sometimes it is problematic for users to distinguish JavaScript from Java. Answer: JavaScript is an Object Based Programming language. It could be used with most of the browsers.
  2. Question: How can we use an isNaN function? Answer: If the number of the argument is false, isNaN can make it true.
  3. Question: What is a prompt box? Answer: with the help of prompt box user will be able to enter input by providing a text book.
  4. Question: what the keyword “this” means in JavaScript? Answer: “This” refers to the object from the place where it was called.
  5. Question: What symbol should be used for comments in JavaScript? Answer: you should use “//” for comments in a single line and “/” for multi-line.
  6. Question: Can you explain what the looping structures in JavaScript are? Answer: There are three looping structures in this programming language: for loops, while loops and do-while loops.
  7. Question: Please, tell about escape characters. Answer: we use escape characters when we are working with single or double quotes, apostrophes and ampersands.
  8. Question: is it possible to hide JavaScript code from browsers that doesn`t support JavaScript? Answer: yes, it is possible. To make it you just need to add “<!-“ without the quotes in the code after the <script> tag. Old browser won`t treat this JavaScript code like long HTML comment. With the help of the added marks, it will take codes as one-line comments.
  9. Question: what is unshift method in JavaScript? Answer: this method looks like the push method. It will work at the beginning of the array and is used to prepend one ore many elements to the beginning.
  10. Question: You mentioned Push method. Tell us about it. Answer: this method has the same description. The only difference is that with it you will prepend elements to the end of the array.

That is our top javascript interview questions. All of them weren`t so hard, so you have an opportunity to practice the answers. With this questions and answers you will have better understanding of the JavaScript.


Igor Grigorenko

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