JavaScript Operators

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JavaScript Operators

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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)

Try it yourself »

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JavaScript Arithmetic Operators

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

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

The addition operator (+) adds numbers:

Adding

var x = 5;
var y = 2;
var z = x + y;

Try it Yourself »

The multiplication operator (*) multiplies numbers.

Multiplying

var x = 5;
var y = 2;
var z = x * y;

Try it Yourself »

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

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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;

Try it Yourself »

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

Assignment

var x = 10;
x += 5;

Try it Yourself »

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JavaScript String Operators

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

	문자열을 사용하는 경우 +연산자를 연결연산자라고 한다.

Example

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

The result of txt3 will be:

John Doe

Try it Yourself »

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

Try it Yourself »

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Adding Strings and Numbers

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

Try it Yourself »

수 + 문자열 = 문자열

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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.

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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.