8. 자바스크립트 연산자(JS Operators)

[참고] http://www.w3schools.com/js/js_operators.asp

Example

변수들에 값을 할당하고 그들을 같이 더한다.

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

Try it Yourself »

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JavaScript Arithmetic Operators(자바스크립트 산술 연산자)

산술 연산자는 변수와(나) 값 사이에 산술 연산을 수행하기 위해 사용된다.

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

더하기 연산자(+)는 값을 더한다.

Adding

var x = 5;
var y = 2;
var z = x + y;

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The subtraction operator (-) subtracts a value.

Subtracting

var x = 5;
var y = 2;
var z = x - y;

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The multiplication operator (*) multiplies a value.

Multiplying

var x = 5;
var y = 2;
var z = x * y;

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The division operator (/) divides a value.

Dividing

var x = 5;
var y = 2;
var z = x / y;

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The modular operator (%) returns division remainder.

Modulus

var x = 5;
var y = 2;
var z = x % y;

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The increment operator (++) increments a value.

Incrementing

var x = 5;
x++;
var z = x;

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The decrement operator (--) decrements a value.

Decrementing

var x = 5;
x--;
var z = x;

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JavaScript Assignment Operators

Assignment operators are used to 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;

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The += assignment operator adds a value to a variable.

Assignment

var x = 10;
x += 5;

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The -= assignment operator subtracts a value from a variable.

Assignment

var x = 10;
x -= 5;

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The *= assignment operator multiplies a variable.

Assignment

var x = 10;
x *= 5;

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The /= assignment divides a variable.

Assignment

var x = 10;
x /= 5;

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The %= assignment operator assigns a remainder to a variable.

Assignment

var x = 10;
x %= 5;

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JavaScript String Operators

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

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

Example

To add two or more string variables together, use the + operator.

txt1 = "What a very";
txt2 = "nice day";
txt3 = txt1 + txt2;

The result of txt3 will be:

What a verynice day

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To add a space between the two strings, insert a space into one of the strings:

Example

txt1 = "What a very ";
txt2 = "nice day";
txt3 = txt1 + txt2;

The result of txt3 will be:

What a very nice day

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or insert a space into the expression:

Example

txt1 = "What a very";
txt2 = "nice day";
txt3 = txt1 + " " + txt2;

The result of txt3 will be:

What a very nice day

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The += operator can also be used to 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(문자와 숫자 더하기)

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

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

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JavaScript Comparison and Logical Operators

Comparison and logical operators are described in the JS Comparisons chapter