Thursday, 13 March 2014

JAVASCRIPT COMMENTS AND VARIABLES



JavaScript Comments:

·         Comments will not be executed by JavaScript.
·         Comments can be added to explain the JavaScript, or to make the code more readable.
·         Single line comments start with //.
  • Multi line comments start with /* and end with */.

JavaScript Variables:

·         JavaScript variables can be used to hold values (x=5) or expressions (z=x+y).
·         Variable can have short names (like x and y) or more descriptive names (age, sum, total_volume).
  • Variable names are case sensitive (y and Y are different variables)

Declaring JavaScript Variables

·         You declare JavaScript variables with the var keyword:
·         In Javascript, when you're setting up a variable you start with the letters var (short for variable, of course). After a space, you then need to come up with a name for your variable (like a). You can't have spaces in your variable

The name can be almost anything you want. But there are some important considerations. These are:
·         You can't start your variable name with a number
·         The variable should contain only letters, numbers ( but not the first character of the variable), a dollar sign ($) and an underscore ( _ )
·         Variable names must begin with a letter
Here are some valid variable names:
number1
number_1
$firstName
And here are some invalid variables names:
1number
mob number
"firstName"
Literal: - Literal is variable value, constant value or expression, which represents a value.

No comments: