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## 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)

JavaScript Arithmetic Operators

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

Operator Description
- Subtraction
* Multiplication
/ Division
% Modulus
++ Increment
-- Decrement

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

The multiplication operator (*) multiplies numbers.

Multiplying

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

JavaScript Assignment Operators

Assignment operators assign values to JavaScript variables.

Operator Example Same As
= x = y x = y
+= x += y x = x + y
-= x -= y x = x - y
*= x *= y x = x * y
/= x /= y x = x / y
%= x %= y x = x % y

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

Assignment

var x = 10;

Assignment

var x = 10;
x += 5;

JavaScript String Operators

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

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

Example

txt1 = "John";
txt2 = "Doe";
txt3 = txt1 + " " + txt2;

The result of txt3 will be:

John Doe

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

Example

txt1 = "What a very ";
txt1 += "nice day";

The result of txt1 will be:

What a very nice day

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

Example

x = 5 + 5;
y = "5" + 5;
z = "Hello" + 5;

The result of x, y, and z will be:

10
55
Hello5

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

JavaScript Comparison and Logical Operators

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
? ternary operator

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

JavaScript Type Operators

Operator Description
typeof Returns the type of a variable
instanceof Returns true if an object is an instance of an object type

Type operators are described in the JS Type Conversion chapter.

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