In this article, I am going to explain how to use TypeScript nested If-Else statements. Using nested If-Else statements, we will find the grade of any student by entering his or her marks. 
 
The syntax of a TypeScript nested  If Else is: 
     - If(Condition)    
 
     - {    
 
     -   
 
     - }    
 
     - Else   
 
     - {    
 
     -   If(Condition)   
 
     -   {    
 
     -     
 
     -   }    
 
     -   Else   
 
     -   {    
 
     -     If(Condition)   
 
     -     {    
 
     -       
 
     -     }    
 
     -     Else    
 
     -     {    
 
     -     }    
 
     -   }    
 
     - }     
 
 
 
Now to see how a nested If-Else is used, let's use the following steps.
 
Step 1
 
Open Visual Studio and click on "File" -> "New" -> "Project...".
 
Step 2
 
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) {   
 
     -    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 this.
 
 
When I click the OK button it will give a result like this.
 
 
Summary
 
In this article, I explained how to use a nested If-Else in TypeScript.