Basic JavaScript Interview Questions and Answers

1 :: What is JavaScript?

JavaScript is a general-purpose programming language designed to let programmers of all skill levels control the behavior of software objects. The language is used most widely today in Web browsers whose software objects tend to represent a variety of HTML elements in a document and the document itself. But the language can be--and is--used with other kinds of objects in other environments. For example, Adobe Acrobat Forms uses JavaScript as its underlying scripting language to glue together objects that are unique to the forms generated by Adobe Acrobat. Therefore, it is important to distinguish JavaScript, the language, from the objects it can communicate with in any particular environment. When used for Web documents, the scripts go directly inside the HTML documents and are downloaded to the browser with the rest of the HTML tags and content.

JavaScript is a platform-independent, event-driven, interpreted client-side scripting and programming language developed by Netscape Communications Corp. and Sun Microsystems.

Is This Answer Correct?    21 Yes 4 No

2 :: What’s relationship between JavaScript and ECMAScript?

ECMAScript is yet another name for JavaScript (other names include LiveScript). The current JavaScript that you see supported in browsers is ECMAScript revision 3.

Is This Answer Correct?    15 Yes 2 No

3 :: How do you submit a form using JavaScript?

Use document.forms[0].submit()

(0 refers to the index of the form – if we have more than one form in a page, then the first one has the index 0, second has index 1 and so on).

Is This Answer Correct?    15 Yes 1 No

4 :: How to read and write a file using JavaScript?

I/O operations like reading or writing a file is not possible with client-side JavaScript. However , this can be done by coding a Java applet that reads files for the script

Is This Answer Correct?    8 Yes 7 No

5 :: How to detect the operating system on the client machine?

In order to detect the operating system on the client machine, the navigator.appVersion string (property) should be used.

Is This Answer Correct?    15 Yes 2 No