JavaScript Control Statements – Conditional Statements
By Akanksha MushamHere, we will learn Control statements – conditional statements in JavaScript.
Control Statements decide according to the condition whether a statement should be executed or not. In this post, we further go into detail about these control statements.
This post is to give a basic introduction to control statements in Javascript. At the end of this article, you will clearly understand the usage of conditional statements.
Types of Control Statements in JavaScript
- Conditional statements
- Loop /Iterative Statements
Let’s understand them with the examples:
- Conditional Statements: if, if-else, else-if ladder, switch
IF Statement
The syntax for if statement in JavaScript.
if(condition){
//block of code
}example:
<html lang="en">
<head>
<title>if statement</title>
<script language="javascript" type="text/javascript" >
var a = window.prompt("Enter a number", "0");
a = parseInt(a);
if(a<100){
document.writeln("The number is less than 100");
}
</script>
</head>
<body>
</html>
IF-ELSE Statement
The syntax for the if-else statement in JavaScript.
if(condition){
//block of code
}else{
//block of code
}example:
<!doctype html>
<html lang="en">
<head>
<title>if-else statement</title>
<script language="javascript" type="text/javascript" >
var a = window.prompt("Enter a number", "0");
a = parseInt(a);
var b= parseInt(prompt("Enter b number"));
if(a > b)
window.alert("The greatest is " +a);
else
alert("The greatest is " +b);
</script>
</head>
<body>
</html>
ELSE-IF Statement
The syntax for the else-if statement in JavaScript.
if(condition1){
//logic
}else if(condition2){
//logic
}else{
//logic
}example:
<!-- Arranging 3 numbers in order -->
<!doctype html>
<html lang="en">
<head>
<title>nested if statement</title>
</head>
<body>
<script language="javascript" type="text/javascript" >
var a = parseInt(window.prompt("Enter Marks Sub1"));
var b= parseInt(prompt("Enter Marks Sub2"));
var c= parseInt(prompt("Enter Marks Sub3"));
var avg=(a+b+c)/3;
if(avg >= 70)
alert("First With Distinction");
else if(avg >=60 && avg <70)
alert("First Class");
else if(avg >=50 && avg <60)
alert("Second Class");
else if(avg >=40 && avg <50)
alert("Third Class");
else
alert("Fail");
</script>
</body>
</htmlSWITCH Statement
The syntax for the switch statement in JavaScript.
switch(expression) {
case x:
// block of code
break;
case y:
// block of code
break;
default:
// default block
}example:
<!-- finding the grade using switch -->
<html>
<head>
<title> switch </title>
</head>
<script language="javascript" type="text/javascript">
var n1 = parseInt(window.prompt("Enter the marks in Sub1"));
var n2 = parseInt(window.prompt("Enter the marks in Sub2"));
var n3 = parseInt(window.prompt("Enter the marks in Sub3"));
var avg= (n1+n2+n3)/3;
var ch = parseInt(avg/10); //parse to int
switch(ch)
{
case 10:
case 9:
case 8:
case 7: window.alert("Distinction");break;
case 6: window.alert("First Class");break;
case 5: window.alert("Second Class");break;
case 4: window.alert("Third Class ");break;
default: window.alert("Fail ");
}
</script>
</body>
</html>
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