types of conditional statements in javascript

types of conditional statements in javascript

Introduction: JavaScript, being a versatile and widely used programming language, offers several ways to control the flow of your code. Conditional statements are fundamental constructs in programming that allow you to execute different blocks of code based on certain conditions. In JavaScript, these conditional statements are crucial for creating dynamic and interactive web applications. In this article, we’ll delve into the various types of conditional statements in JavaScript along with practical examples to illustrate their usage.

1) if Statement:

The if statement is one of the most basic conditional statements in JavaScript. It allows you to execute a block of code if a specified condition evaluates to true.

Syntax-

if (condition)

{

Statement // true block

}

Example-1

<html>
<script>
var x=prompt(“Enter any number”)
if (x>20)
{
alert(x+ ” is greater than 20″);
}
</script>
</html>

Output

If we enter x value is 25 then you will get the following output

25 is greater than 20

2) if…else Statement:

The if…else statement extends the functionality of the if statement by providing an alternative block of code to execute when the condition is false.

Syntax-

if (condition)

{

Statement // true block

}

else

{

Statement // false block

}

Example-1

<html>
<script>
var x=prompt(“Enter any number”)
if (x>20)
{
alert(x+ ” is greater than 20″);
}
else
{
alert(x+ ” is less than 20″);
}

</script>
</html>

Output

Enter any number-14

14 is less than 20

Example-2

<html>
<script>
var a=parseInt(prompt(“enter the value of a”))
var b=parseInt(prompt(“enter the value of b”))
if (a>b)
{
document.write(a+” is greater than “+b)
}
else
{
document.write(b+” is greater than “+a)
}
</script>
</html>

Output

First Run

Enter the value of a 40

Enter the value of b 25

40 is greater than 25

Second Run

Enter the value of a 60

Enter the value of b 85

85  is greater than 60

Example-3

<html>
<script>
var n=parseInt(prompt(“enter any number”))
if (n%2==0)
{
document.write(n+” is even”)
}
else
{
document.write(n+” is odd”)
}
</script>
</html>

Output

First Run-

Enter any number 24

24 is even

Second Run

Enter any number 13

13 is odd

3) if…else if…else Statement:

This statement allows you to evaluate multiple conditions and execute different blocks of code accordingly.

if (condition 1)

{

Statement // true block

}

else if(condition 2)

{

Statement // true block

}

else

{

Statement //code to be execute if neither condition 1 nor condition 2 is true

}

Example-1

<html>
<script>
var n=parseInt(prompt(“enter any number…”))
if (n>20)
{
document.write(n+ ” is greater than 20″)
}
else if(n<20)
{
document.write(n+ ” is less than 20″)
}
else if(n==20)
{
document.write(n+ ” is equal to 20″)
}
else
{
document.write(“Invalid Input”)
}
</script>
</html>

Output

First Run-

Enter any number

14

14 is less than 20

Second Run

Enter any number

20

20 is equal to 20

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Example-2

<html>
<script>
var a=parseInt(prompt(“enter first number…”))
var b=parseInt(prompt(“enter second number…”))
var c=parseInt(prompt(“enter third number…”))
if (a>b && a>c)
{
document.write(a+ ” is greater than “+b+” and “+c)
}
else if(b>a && b>c)
{
document.write(b+ ” is greater than “+a+” and ” +c)
}

else
{
document.write(c+” greater than “+b+” and “+a)
}
</script>
</html>

Output

enter first number… 50

enter second number…80

enter third number…10

80 is greater than 50 and 10

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4) switch Statement

The switch statement provides an alternative way to handle multiple conditions more efficiently than chaining if…else if statements.

switch(n)

{

case 1:

execute code block 1

break;

case 2:

execute code block 2

break;

…………………

………………..

default:

code to be executes if it is different from case 1 and case 2

}

Example-1

<html>
<script>
var ch=parseInt(prompt(“enter your choice…”))
switch(ch)
{
case 1:
document.write(“Monday”);
break;
case 2:
document.write(“Tuesday”);
break;
case 3:
document.write(“Wednesday”);
break;
case 4:
document.write(“Thursday”);
break;
case 5:
document.write(“Friday”);
break;
case 6:
document.write(“Saturday”);
break;
case 7:
document.write(“Sunday”);
break;
default:
document.write(“invalid Choice….”)
}
</script>
</html>

Output

Enter your choice 3

Wednesday

Enter Your choice 9

Invalid Choice

5) Ternary Operator (Conditional Operator):

The ternary operator (condition ? expression1 : expression2) is a concise way to write conditional statements. It evaluates a condition and returns one of two expressions based on whether the condition is true or false.

Example

<html>
<script>
var marks = prompt(‘Enter your marks :’);
// check the condition
var result = (marks >= 40) ? ‘pass’ : ‘fail’;
alert(result);
</script>
</html>

Conclusion: Conditional statements are indispensable tools in JavaScript programming for implementing logic and making decisions based on different conditions. Understanding how to use if, if…else, if…else if…else, switch, and the ternary operator enables you to write more efficient and expressive code. By mastering these conditional statements, you’ll have greater control over the flow of your JavaScript programs, paving the way for building dynamic and interactive web applications.

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