Introduction
Today I am going to explain how to use nested If-Else statements in TypeScript. Using nested If-Else statements I explain how to find the grade of any student by entering his or her marks in TypeScript. The syntax of a nested If-Else is:
If(Condition)
{
//If condition is true then write the statement here
}
Else //if condition is false then cursor go to else part
{
If(Condition) //again here check the condition under the else part
{
//If condition is true then write statement here
}
Else //if condition is false then cursor go to else part
{
If(Condition) //again here check the condition under the else part
{
//If condition is true then write statement here
}
Else
{
}
}
}
Now to see how the nested If-Else is used let's use the following.
Step 1
Open Visual Studio 2012 and click on "File" -> "New" -> "Project...".
Step 2
A window is shown, in this select HTML Application for TypeScript under Visual C# and give the name of your application and then click ok.
Step 3
Open the app.ts file and write the following code in it:
class Nested_IfElse {
constructor () {
}
GradingSystem() {
var n: number;
var s = 0;
n = parseInt(prompt("Enter the marks of any student"));
if (n >= 80) {
alert(" You got A grade");
}
else if (n >= 60) { // Note the space between else & if
alert(" You got B grade");
}
else if (n >= 40) {
alert(" You got C grade");
}
else if (n < 40) {
alert(" You Failed in this exam");
}
}
}
window.onload = () =>
{
var greeter = new Nested_IfElse();
greeter.GradingSystem();
};
Step 4
Open the app.js file and write the following code in it:
var Nested_IfElse = (function () {
function Nested_IfElse() {
}
Nested_IfElse.prototype.GradingSystem = function () {
var n;
var s = 0;
n = parseInt(prompt("Enter the marks of any student"));
if (n >= 80) {
alert(" You got A grade");
} else {
if (n >= 60) {
alert(" You got B grade");
} else {
if (n >= 40) {
alert(" You got C grade");
} else {
if (n < 40) {
alert(" You Failed in this exam");
}
}
}
}
};
return Nested_IfElse;
})();
window.onload = function () {
var greeter = new Nested_IfElse();
greeter.GradingSystem();
};
Step 5
Write the following code in the default.htm file:
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" />
<title>TypeScript HTML App</title>
<link rel="stylesheet" href="app.css" type="text/css" />
</head>
<body>
<h1>Nested If Else Example</h1>
<div id="content">
<script src="app.js"></script>
</div>
</body>
</html>
Step 6
Now run the application; the output will look like:
![Output-of-nested-ifelse-in-typescript.jpg]()
When I click the ok button it will give the result as:
![Display-result-of-nested-ifelse-in-Typescript.jpg]()
Summary
In this article I explained how to use nested If-Else in TypeScript.