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Conditional Statements In JavaScript

Introduction

 
In this article, we will learn about Conditional Statements in JavaScript. These statements are also called Selection Statements.
 
The Conditional Statements in JavaScript:
  1. If Statement
  2. If Else Statement
  3. Elseif Statement
  4. Switch Case Statement

If Statement

 
If Statements are used for the purpose of decision making; they evaluate the statement if the condition is true. To check if the given If condition is satisfied, If Statement is executed; otherwise the condition is false to exit the If condition.
 
Syntax
  1. If (condition)  
  2. {   
  3.      Statement; //given condition is true execute the statement  
  4. }  
Example
  1. <!DOCTYPE html>  
  2. <html>  
  3. <head>  
  4.     <title>if Condition</title>  
  5. </head>  
  6. <body>  
  7.     <h1>Conditional Statement in JavaScript</h1>  
  8.     <script type="text/javascript">  
  9.         var percentage =(prompt("Enter Your Mark"))  
  10.         if (percentage >= 40)   
  11.         {  
  12.             document.write("You Mark is Pass"); //given condition is true execute the statement  
  13.         }  
  14.     </script>  
  15. </body>  
  16. </html>  
Output
 
Conditional Statements In JavaScript
 
Conditional Statements In JavaScript
 

If else Statement

 
If else Statement is an improvement over if Statement. It evaluates the statement if the condition is true or false. In this statement, the given If condition is true means to execute the if Statement. On the other hand, if the condition is false it means to execute another block.
 
Syntax
  1. if (Condition)  
  2. {  
  3.       Statement; //true  
  4. }  
  5. else  
  6. {  
  7.       Statement; //false  
  8. }  
Example
  1. <!DOCTYPE html>  
  2. <html>  
  3. <head>  
  4.     <title>if Condition</title>  
  5. </head>  
  6. <body>  
  7.     <h1>Conditional Statement in JavaScript</h1>  
  8.     <script type="text/javascript">  
  9.         var percentage =(prompt("Enter Your Mark"))  
  10.         if (percentage >= 40)   
  11.         {  
  12.             document.write("You Mark is Pass"); //given condition is true execute the statement  
  13.         }  
  14.         else  
  15.         {  
  16.             document.write("You Mark is Fail"); //given condition is false execute the statement  
  17.         }  
  18.     </script>  
  19. </body>  
  20. </html>  
Output
 
Conditional Statements In JavaScript
 
Conditional Statements In JavaScript 
 

Else If Statement

 
It is another decision-making statement. It evaluates the Statement only if condition is true from several conditions, elseif statement can be used many times in a program; if the two conditions are false it means else Statement is executed.
 
Syntax
  1. If (condition 1)  
  2. {  
  3.       statement 1; //true  
  4. }  
  5. elseif (condition 2)  
  6. {  
  7.       statement 2; //true  
  8. }  
  9. else  
  10. {  
  11.       statement; //evaluate if condition is false  
  12. }  
Example
  1. <!DOCTYPE html>  
  2. <html>  
  3. <head>  
  4.     <title>if Condition</title>  
  5. </head>  
  6. <body>  
  7.     <h1>Conditional Statement in JavaScript</h1>  
  8.     <script type="text/javascript">  
  9.         var mark =(prompt("Enter Your Mark"))  
  10.         if (mark>= 90 && mark <=100)   
  11.         {  
  12.             document.write("A Grade"); //given condition is true execute the statement  
  13.         }  
  14.         else if (mark >= 80 && mark <=89)   
  15.         {  
  16.             document.write("B Grade"); //given condition is true execute the statement  
  17.         }  
  18.         else if (mark >= 70 && mark <= 79)   
  19.         {  
  20.             document.write("C Grade"); //given condition is true execute the statement  
  21.         }  
  22.         else if (mark >= 60 && mark <= 69)   
  23.         {  
  24.             document.write("D Grade"); //given condition is true execute the statement  
  25.         }  
  26.         else if (mark >= 35 && mark <= 59)   
  27.         {  
  28.             document.write("E Grade"); //given condition is true execute the statement  
  29.         }  
  30.         else  
  31.         {  
  32.             document.write("Fail"); //given condition is false execute the statement  
  33.         }  
  34.     </script>  
  35. </body>  
  36. </html>  
Output
 
Conditional Statements In JavaScript
Conditional Statements In JavaScript 
 
Below 35 mark 
 
Conditional Statements In JavaScript 
 
Conditional Statements In JavaScript
 

Switch Case

 
Switch Case Statement is a control Statement, it is better than If else statements. To improve the readability of a program multiple if else Statements can be replaced with Switch Statements. In Switch Case Statements, using the break statement will cause an immediate exit from switch statement as soon as the code under the code is executed.
 
Syntax
  1. Switch (expression){  
  2. Case 1:  
  3.    Statement;  
  4.    Break;  
  5. Case 2:  
  6.    Block of Statement:  
  7.    Break:  
  8. Default:  
  9.    Block of statement:  
  10.   }  
Example
  1. <!DOCTYPE html>  
  2. <html>  
  3. <head>  
  4.     <title>Conditional Statement</title>  
  5. </head>  
  6. <body>  
  7.     <h1>Switch Case in JavaScript</h1>  
  8.     <script type="text/javascript">  
  9.         var days = 3;  
  10.         switch (days)  
  11.         {  
  12.             case 1:  
  13.                 document.write("Sunday");  
  14.                 break;  
  15.             case 2:  
  16.                 document.write("Monday");  
  17.                 break;  
  18.             case 3:  
  19.                 document.write("Teusday");  
  20.                 break;  
  21.             case 4:  
  22.                 document.write("Wednesday");  
  23.                 break;  
  24.             case 5:  
  25.                 document.write("Thusday");  
  26.                 break;  
  27.             case 6:  
  28.                 document.write("Friday");  
  29.                 break;  
  30.             case 7:  
  31.                 document.write("Saturday");  
  32.                 break;  
  33.             default:  
  34.                 document.write("There is no day");  
  35.                 break;  
  36.         }  
  37.     </script>  
  38. </body>  
  39. </html>  
Output
 
Conditional Statements In JavaScript
 

Conclusion

 
In this article, we have seen about Conditional Statements in JavaScript. I hope this article is useful for you. Thank you. 


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