Showing posts with label Factorial Solver in Javascript. Show all posts
Showing posts with label Factorial Solver in Javascript. Show all posts

Wednesday, September 16, 2015

Factorial Solver in Javascript

A factorial program that I wrote using JavaScript as my programming language what does the program will do is to ask the user to enter a number and then our program will compute the factorial value in a given number by the user.

If you  have some questions please send me an email at jake.r.pomperada@gmail.com and jakerpomperada@yahoo.com. My mobile number here in the Philippines is 09173084360.





Sample Program Output


Program Listing

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Factorial Solver in Javascript</title>
</head>
<style>
body,label {
     background-color:lightgreen;
     font-family:arial;
     color:blue;
     font-size:18px;
     font-weight:bold;
     }
label{
    display: table-cell;
    text-align: right;
}
input {
  display: table-cell;
}
div.row{
    display:table-row;
}
button {
    font-family: 'arial';
    font-size:18px;
    color:red;
}
input[type="number"] { 
    font-family: 'arial';
    font-size:18px;
    color:red;
    height: 25px;
    width: 38px;
}
</style>
<body>
<h2> Factorial Solver in Javascript </h2>
 <div class="row"><label>Enter a Number</label>
      &nbsp;&nbsp;&nbsp;
      <input type="number" size="2" id="values" maxlength="2" onkeypress="return isNumber(event)" 
      required autofocus><br></div>
  <br>
<button title="Click here to find the factorial value.">Solve Factorial</button>
&nbsp;&nbsp;&nbsp;&nbsp;
<button title="Click here to clear the text box.">Clear</button><br>
<br><br>
<div id="result"></div>
<script>
var button = document.getElementsByTagName('button');

button[0].onclick = display_result;
button[1].onclick = clear_text;

document.onload = function() {
   document.getElementById('values').focus();
};
    // function to compute the factorial value of a given number.
function find_factorial_value(number_value)
{
   if (number_value < 0) {
       return -1;
   }
  
   else if (number_value == 0) {
       return 1;
   }
   
   else {
       return (number_value * find_factorial_value(number_value - 1));
   }
}

// This function will display the computed factorial results.
function display_result() {
var numbers = document.getElementById("values").value;
var result = find_factorial_value(numbers);
 
if (document.getElementById("values").value == '') {
       alert("Cannot be empty. Please put a numerical value.");
       document.getElementById('values').focus();
       
   }
else {
 document.getElementById('result').innerHTML = "The factorial value of "
        + numbers + " is " + result + ".";
}
}
// This function will clear the text box.
function clear_text() {
document.getElementById("values").value="";
document.getElementById("result").innerHTML="";
document.getElementById("values").focus();
}

// This function will only allow numerical value in the text box.
function isNumber(evt) {
    evt = (evt) ? evt : window.event;
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
        return false;
    }
    return true;
}
</script>
</body>
</html>