Check a number is Prime or not using JavaScript
A prime number is a number that is divisible by 1 and itself only. First few prime numbers are: 2, 3, 5, 7, 11, 13, 17, …
A JavaScript uses the DOM model to check the input number is prime or not and display its corresponding alert message on the screen.
Examples:
Input : 4 Output : Not Prime Input : 5 Output : Prime
Example 1: This example display the result by using alert function.
<!DOCTYPE html> <html> <head> <title> Check a number is Prime or not using JavaScript </title> <script type= "text/javascript" > // Function to check prime number function p() { var n, i, flag = true ; // Getting the value form text // field using DOM n = document.myform.n.value; n = parseInt(n) for (i = 2; i <= n - 1; i++) if (n % i == 0) { flag = false ; break ; } // Check and display alert message if (flag == true ) alert(n + " is prime" ); else alert(n + " is not prime" ); } </script> </head> <body> <center> <h1>GeeksforGeeks</h1> <h4>check number is prime or not</h4> <hr color= "Green" > <form name= "myform" > Enter the number: <input type= "text" name=n value= "" > <br><br> <input type= "button" value= "Check" onClick= "p()" > <br> </form> </center> </body> </html> |
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Output:
- Before checking the number:
- After checking the number:
Example 2: This example checks a given number is prime or not and display result on the console.
<!DOCTYPE html> <html> <head> <title> Check a number is Prime or not using JavaScript </title> <style> body { border:2px solid black; width:400px; height:150px; text-align:center; } h1 { color:green; } </style> <script type= "text/javascript" > // Function to check for prime number function checkPrime() { var n, i, flag = true ; // Getting the value form the // text field using DOM n = document.myform.n.value; n = parseInt(n) for (i = 2; i <= n - 1; i++) if (n % i == 0) { flag = false ; break ; } // Check and display output if (flag == true ) console.log(n + " is prime" ); else console.log(n + " is not prime" ); } </script> </head> <body> <h1>GeeksforGeeks</h1> <h4>check number is prime or not</h4> <form name= "myform" > Enter the number: <input type= "text" name=n value= "" > <input type= "button" value= "Check" onClick= "checkPrime()" > <br> </form> </center> </body> </html> |
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Output:
- Before checking the number:
- After checking the number: