Conditional statements are used to make decisions in JavaScript. 

StatementPurposeExample
ifExecute code if condition is trueif(age > 18)
if...elseExecute one block if true and another if falseif(age > 18) else
else ifCheck multiple conditionselse if(marks > 60)
switchSelect one block from many optionsswitch(day)
ternaryShort form of if...elseage > 18 ? "Yes" : "No"


 

1. if Statement:

Syntax:

if(condition){
   // code
}

Example:

let age = 20;
if(age >= 18){
   console.log("Adult");
}

 

2. if...else Statement:

Syntax:

if(condition){
   // true block
}else{
   // false block
}

Example:

let age = 15;
if(age >= 18){
   console.log("Eligible");
}else{
   console.log("Not Eligible");
}

3. else if Statement

Example:

let marks = 75;
if(marks >= 90){
   console.log("Grade A");
}
else if(marks >= 60){
   console.log("Grade B");
}
else{
   console.log("Fail");
}

4. switch Statement

Example:

let day = 2;
switch(day){
   case 1:
      console.log("Monday");
      break;
   case 2:
      console.log("Tuesday");
      break;
   default:
      console.log("Invalid Day");
}

5. Ternary Operator

Short form of if...else.

Syntax:

condition ? true_value : false_value;

Example:

let result = (age >= 18) ? "Adult" : "Minor";