JavaScript Interview Questions（1）

1.What is JavaScript?

• JavaScript is a scripting language.
• It is different from Java language.
• It is object-based, lightweight, cross-platform translated language.
• It is widely used for client-side validation.
• The JavaScript Translator (embedded in the browser) is responsible for translating the JavaScript code for the web browser.

2. List some features of JavaScript.

• Lightweight
• Interpreted programming language
• Good for the applications which are network-centric
• Complementary to Java
• Complementary to HTML
• Open source

3. List some of the advantages of JavaScript.

• Server interaction is less
• Feedback to the visitors is immediate
• Interactivity is high
• Interfaces are richer

4.List some of the disadvantages of JavaScript.

• No support for multithreading
• No support for multiprocessing
• Reading and writing of files is not allowed
• No support for networking applications.

5.Define a named function in JavaScript.

The function which has named at the time of definition is called a named function.

function msg()  
{  
  document.writeln("Named Function");  
}  
msg();  

6.Name the types of functions

• Named - These type of functions contains name at the time of definition.

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

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

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

7.Define anonymous function

• It is a function that has no name.
• These functions are declared dynamically at runtime using the function operator instead of the function declaration.
• The function operator is more flexible than a function declaration.
• It can be easily used in the place of an expression.

8.Can an anonymous function be assigned to a variable?

Yes, you can assign an anonymous function to a variable.

9. In JavaScript what is an argument object?

The variables of JavaScript represent the arguments that are passed to a function.

10.Define closure.

• In JavaScript, we need closures when a variable which is defined outside the scope in reference is accessed from some inner scope.

var num = 10;  
function sum()   
{  
document.writeln(num+num);  
}   
sum();