JAVA SCRIPT- LEARN TO BUILD WEBSITES

  Here we are learning about

• Values, Variables, and Literals

• Expressions and Operators

• Regular Expressions

• Statements

• Functions

• Working with Objects

• Details of the Object Model

first let us describe wat is Values, Variables, and Literals:

VALUES:

JavaScript recognizes the following types of values:

• Numbers, such as 42 or 3.14159.

• Logical (Boolean) values, either true or false.

• Strings, such as “Howdy!”.

• null, a special keyword denoting a null value; null is also a primitive

value. Because JavaScript is case sensitive, null is not the same as Null,

NULL, or any other variant.

• undefined, a top-level property whose value is undefined; undefined is

also a primitive value.

This relatively small set of types of values, or data types, enables you to

perform useful functions with your applications. There is no explicit distinction

between integer and real-valued numbers. Nor is there an explicit date data

type in JavaScript. However, you can use the Date object and its methods to

handle dates.

Objects and functions are the other fundamental elements in the language. You

can think of objects as named containers for values, and functions as

procedures that your application can perform.

Data Type Conversion:

JavaScript is a dynamically typed language. That means you do not have to

specify the data type of a variable when you declare it, and data types are

converted automatically as needed during script execution. So, for example,

you could define a variable as follows:

var answer = 42

And later, you could assign the same variable a string value, for example,

answer = "Thanks for all the fish..."

Because JavaScript is dynamically typed, this assignment does not cause an

error message.

In expressions involving numeric and string values with the + operator,

JavaScript converts numeric values to strings. For example, consider the

following statements:

x = "The answer is " + 42 // returns "The answer is 42"

y = 42 + " is the answer" // returns "42 is the answer"

In statements involving other operators, JavaScript does not convert numeric

values to strings. For example:

"37" - 7 // returns 30

"37" + 7 // returns 377