if else statement, switch statement, operators

 

•JavaScript If…Else Statements

–if ( CONDITION ) {

–}

–if ( CONDITION ) {

–} else {

–}

–if ( CONDITION ) {

–} else if ( CONDITION ) {

–}

–if ( CONDITION ) {

–} else if ( CONDITION ) {

–} else {

–}


 

•JavaScript Switch Statement

–switch(n) {

– case 1:

– execute code block 1

– break;

– case 2:

– execute code block 2

– break;

– default:

– code to be executed if n is

– different from case 1 and 2

–}

JavaScript Operators
 

Operator	Description	Example	Result
+	Addition	x=2 y=2 x+y	4
-	Subtraction	x=5 y=2 x-y	3
*	Multiplication	x=5 y=4 x*y	20
/	Division	15/5 5/2	3 2.5
%	Modulus (division remainder)	5%2 10%8 10%2	1 2 0
++	Increment	x=5 x++	x=6
--	Decrement	x=5 x--	x=4

 

Operator	Example	Is The 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

 

Operator	Description	Example
==	is equal to	5==8 returns false
===	is equal to (checks for both value and type)	x=5 y="5" x==y returns true x===y returns false
!=	is not equal	5!=8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

 

–-&&

§    If first operand is truthy

–        then result is second operand

–            else result is first operand

–-||

§    If first operand is truthy

–        then result is first operand

–            else result is second operand

Operator	Description	Example
&&	and	x=6 y=3 (x < 10 && y > 1) returns true
||	or	x=6 y=3 (x==5 || y==5) returns false
!	not	x=6 y=3 !(x==y) returns true

 

-String

§txt1="What a very";

§txt2="nice day!";

§txt3=txt1+txt2;

-Conditional

§variablename = (condition) ? value1 : value2;

 

-alert

§var result = alert("sometext");

§alert(result); // undefined

-confirm

§var result = confirm("sometext");

§alert(result); // 확인:true, 취소:false

-prompt

§var result = prompt("sometext", "defaultvalue");

§alert(result); // 확인:string, 취소:null