Page 337 - Webapplication11_C11_Flipbook
P. 337
<SCRIPT>
var x = 50;
var y = 20;
var sum = x + y;
document.write("The sum is " + sum);
</SCRIPT>
</BODY>
</HTML>
When we view the preceding web page in the web browser, the following output appears:
Declaring Constants
A constant is a type of variable whose value cannot be modified while the program is running. Constants in JavaScript
are declared using the const type, and the name of the constant is only in uppercase by convention. The JavaScript
constant variable is supported by a large number of browsers. Examples are as follows:
const PI=3.14
const RATE=8.9
Keywords
A keyword is a reserved word that has a special meaning for the JavaScript interpreter. These terms are not allowed
to be used as variable names.
The list of keywords is as follows:
break else new var
case finally return void
catch for switch whie
continue function this with
default if throw delete
in try do instance of
type of interface null undefined
Comments
A comment is used to add notes in your code or to disable sections of code without deleting them. Comments are
ignored by the JavaScript interpreter. There are two types of comments in JavaScript: single line and multi-line. Single
line comments are added by using // and multi-line comments are added by using /* and */.
JavaScript Part 1 335

