[08] JavaScript Operators

JavaScript

MorningPhys 2015. 7. 13. 18:56

JavaScript Operators

Example

Assign values to variables and add them together:

var x = 5; // assign the value 5 to x
var y = 2; // assign the value 2 to y
var z = x + y; // assign the value 7 to z (x + y)

<!DOCTYPE html>
<html>
<body>

<h1>JavaScript Operators</h1>

<p>x = 5, y = 2, calculate z = x + y, and display z:</p>

</body>
</html>

Arithmetic operators are used to perform arithmetic on numbers (literals or variables).

The addition operator (+) adds numbers:

var x = 5;
var y = 2;
var z = x + y;

The multiplication operator (*) multiplies numbers.

var x = 5;
var y = 2;
var z = x * y;

You will learn more about JavaScript operators in the next chapters.

Assignment operators assign values to JavaScript variables.

The assignment operator (=) assigns a value to a variable.

var x = 10;

The addition assignment operator (+=) adds a value to a variable.

var x = 10;
x += 5;

The + operator can also be used to add (concatenate) strings.

When used on strings, the + operator is called the concatenation operator.

<p>The + operator concatenates (adds) strings.</p>

The += assignment operator can also be used to add (concatenate) strings:

<p>The assignment operator += can concatenate strings.</p>

Adding two numbers, will return the sum, but adding a number and a string will return a string:

<p>Adding a number and a string, returns a string.</p>

The rule is: If you add a number and a string, the result will be a string!

Operator	Description
==	equal to
===	equal value and equal type
!=	not equal
!==	not equal value or not equal type
>	greater than
<	less than
>=	greater than or equal to
<=	less than or equal to

Comparison and logical operators are described in the JS Comparisons chapter.