-The shift() method is similar as the pop() method but the difference is that Shift method works at the beginning of the array. 

-The shift() method take the first element off of the given array and returns it. The array on which is called is then altered.

For example

var myarray = ["apple ", "banana ", "mango "]; 

console.log(myarray.shift());

console.log(myarray);

we get the following console output:

apple

["banana ", "mango "];

When we call shift() on an empty array, it will return an undefined value.

Math object has two constant : Math.PI and Math.E

Math object has following functions:

- Math.abs(val1);

It will give absolute value of val1.

- Math.max(val1,val2);

This fuction will return maximum value from val1 and val2.

- Math.random();

This function will return a random number between 0 and 1.

- Math.floor(val1)

This function will returns decimal value of val1

Arrays are created by using new Array() in Java Script.

For example : var employees = new Array();

The elements to this array is assigned as follows :

employees[0] = "Kumar"

employees[1] = "Fedrick"

NaN stands for ‘not-a-number’. The function isNaN determines the argument or the value is a NaN. The function returns true if the argument is not a number, otherwise returns false.

Windows object is top level object in Java script. It contains several other objects such as, document, history, location, name, menu bar etc., in itself. Window object is the global object for Java script that is written at client-side.

Information pertaining to the client browser and system is returned by the navigator object of JavaScript. Navigator object is the top level object for all users.

To send the characters that can not be specified in a URL should be converted into their equivalent hex encoding. To perform this task the methods encodeURI() and decodeURI() are used.

For example, the following code snippet performs the encoding of URL:

<script type="text/javascript">

          var uri = https://www.mysite.com/city?=Banglore; // original URI

          var ncodeuri=encodeURI(uri);

          document.write("<br />ncodeuri”);

          var dcodeuri = decodeURI(ncodeuri); 

          document.write(“<br>/>dcodeuri”);

</script>

Client side java script comprises the basic language and predefined objects which are relevant to running java script in a browser. The client side java script is embedded directly by in the HTML pages. This script is interpreted by the browser at run time.

Server side java script also resembles like client side java script. It has relevant java script which is to run in a server. The server side java scripts are deployed only after compilation.

- External Style Sheets are useful as it keeps the style and content separately and doesn’t allow it to mix with each other. It can control the styles for multiple documents, whereas inline style mixes the content with the style and make the code messier.

- External style sheet allows the creation of various classes in a structured way, whereas inline style sheet can’t create or control class elements.

- External style sheet can use selector and grouping methods to apply styles, whereas inline styles can’t use selector and grouping methods.