Page 71 - Trackpad_V1_Book 8_Flipbook
P. 71
STATEMENTS IN JAVASCRIPT
Commands and instructions given to the
JavaScript interpreter to take some actions
Subject: The confirm( ) Method
are called statements and a collection of
The confirm() method displays a dialog
statements is called a script or a program. box with a specified message, along
Within almost every browser resides with an OK and a Cancel button.
the JavaScript interpreter. We use the
semicolon to terminate a statement but, if
the statements are written in separate lines, then the semicolon can be omitted.
JavaScript statements consist of keywords, variables, operators, expressions and comments.
Let us learn about them in detail.
KEYWORDS
A keyword is a reserved word that has a special meaning for the JavaScript interpreter. Some of
the keywords of JavaScript are:
var, switch, let, for, const, function, if, return, etc.
VARIABLES
A variable is the name of storage location. It stores a value that can be modified later. JavaScript
is a loosely typed language which means it does not require a data type to be declared before
using it. Syntax to declare a variable in JavaScript is:
var <variable name> = <value>;
where var is a keyword, <variable name> is a valid name for the variable and <value> is the value
that you want to assign to the variable.
For example:
var age = 16;
var name = "A"
We can declare multiple variables in the same line in the following way:
var v1 = 1, v2 = 'Delhi', v3;
Variable Naming Conventions
Some of the naming conventions that need to be followed while declaring variables in JavaScript are:
Variable names are case-sensitive which means that the variable name 'AGE' is different
from 'age'.
A variable name must not start with digits 0–9.
Variable names can contain letters, digits, or the symbols $ and _.
A variable name cannot be a reserved keyword.
Dynamic Web Pages in HTML5 69

