Number of Primes

Edemar Oliveira May 26, 2004

The script implements the seive of Erastótenes. It finds all the prime numbers up to one determined value.

The JavaScript Source: Math Related: Number of Primes

Simply click inside the window below, use your cursor to highlight the script, and copy (type Control-c or Apple-c) the script into a new file in your text editor (such as Note Pad or Simple Text) and save (Control-s or Command-s). The script is yours!!!

<!-- THREE STEPS TO INSTALL NUMBER OF PRIMES:

1.  Copy the coding into the HEAD of your HTML document
  2.  Add the onLoad event handler into the BODY tag
  3.  Put the last coding into the BODY of your HTML document  -->

<HEAD>

<script language=javascript>
/*
Script implements the seive of Erastótenes. 
It finds all the prime numbers up to one determined value. 
developed by: Edemar C. Oliveira - edemar@hotmail.com
				www.edemar.cjb.net	
*/
function CriaArray (n) { 
	this.length = n 
	for (var i = 1 ; i <= n ; i++) 
		{ this[i] = 1 } 
}

function infP(){

var i, k;
	var m;
	var npValue =  prompt("type value: ", "" );
	var npSize = parseInt(npValue);

if (npSize <= 0) {
		alert ("invalid value!");
		document.location.reload();
		return false;
	}

var flags = new CriaArray(npSize) ;

for( i=2; i<=flags.length; i++ ){
            if( flags[i] )
                  for( k=i+1; k<=flags.length; k+=i )
                        flags[k] = 0;
    }
	
	if (npSize > 2)
	   m = 2 + ",";
	   
    for( i=0; i<=flags.length; i++  )
       if (flags[i] == 0)
          m += i + ",";

alert("The numer of primes up to - " + npSize + " are : " + m );
} 
</script>

</HEAD>

<!-- Begin

//  End -->
</script>

<p><center>
<font face="arial, helvetica" size"-2">Free JavaScripts provided<br>
by <a href="http://javascriptsource.com">The JavaScript Source</a></font>
</center><p>

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