JavaScript -> Long number sufix

[LXS]

Hi, I'm new here on this forum and I have registered to receive help in certain situations and help others members if I can.
I start with a problem which gives me a headache, I created a prototype function that adds a multiple or submultiple metric string, works in if..if..if case but if I try to compact the code in a shorten way I get an error .
In this case 1e+5 => 100,000, with an alert: alert (1e+5) works perfectly, but when I try this code does not work at all:

var pw = 5;
alert (1e + (pw));

The complete code is at the end, I want to mention that the code below in comment (if...if...if) it works great but is very bad to read and to edit something, so I try to use a loop.
If anyone has a better solution please post it.
Thank you very much, I owe you one!

var ESE = {};
ESE.Component = function()
{
/*
...
...
...
*/
}
ESE.prototype.getPosSufix=function(value) 
{
	var sufix="";
	var rval=value;
	var i,j=0;
	var sTable=
	[
		/*Metric multiples*/
		"yotta","zetta","exa","peta","tera",
		"giga","mega","kilo","hecto","deca",
		/*Metric submultiples*/
		"deci","centi","mili","micro","nano",
		"pico","femto","atto","zepto","yocto"
	];
	for(i=24;i>=1;i=i-3)
	{
		/*if(value>=(1e+(i))&&value<(10e+(i+2)))
		{
			if(i==3 && j==8) {i+=3}
			rval=value*(1e-(i));
			sufix=sTable[j];
		}*/
		alert(1e+0+i);
		j++;
	}
	/*if(value>=1e-24&&value<10e-22)
	{
		rval=value*1e+24;
		sufix="yocto";
	}
	if(value>=1e-21&&value<10e-19)
	{
		rval=value*1e+21;
		sufix="zepto";
	}
	if(value>=1e-18&&value<10e-16)
	{
		rval=value*1e+18;
		sufix="atto";
	}
	if(value>=1e-15&&value<10e-13)
	{
		rval=value*1e+15;
		sufix="femto";
	}
	if(value>=1e-12&&value<10e-10)
	{
		rval=value*1e+12;
		sufix="pico";
	}
	if(value>=1e-9&&value<10e-7)
	{
		rval=value*1e+9;
		sufix="nano";
	}
	if(value>=1e-6&&value<10e-4)
	{
		rval=value*1e+6;
		sufix="micro";
	}
	if(value>=1e-3&&value<10e-1)
	{
		rval=value*1e+3;
		sufix="mili";
	}
	if(value>=1e-2&&value<10e-1)
	{
		rval=value*1e+2;
		sufix="centi";
	}
	if(value>=1e-1&&value<10e-1)
	{
		rval=value*1e+1;
		sufix="deci";
	}
	if(value>=1e+1&&value<10e+1)
	{
		rval=value*1e-1;
		sufix="deca";
	}
	if(value>=1e+2&&value<10e+2)
	{
		rval=value*1e-2;
		sufix="hecto";
	}
	if(value>=1e+3&&value<10e+5)
	{
		rval=value*1e-3;
		sufix="kilo";
	}
	if(value>=1e+6&&value<10e+8)
	{
		rval=value*1e-6;
		sufix="mega";
	}
	if(value>=1e+9&&value<10e+11)
	{
		rval=value*1e-9;
		sufix="giga";
	}
	if(value>=1e+12&&value<10e+14)
	{
		rval=value*1e-12;
		sufix="tera";
	}
	if(value>=1e+15&&value<10e+17)
	{
		rval=value*1e-15;
		sufix="peta";
	}
	if(value>=1e+18&&value<10e+20)
	{
		rval=value*1e-18;
		sufix="exa";
	}
	if(value>=1e+21&&value<10e+23)
	{
		rval=value*1e-21;
		sufix="zetta";
	}
	if(value>=1e+24&&value<10e+26)
	{
		rval=value*1e-24;
		sufix="yotta";
	}*/
	return [rval,sufix];
}

[Philip M]

Try this:-

<script type = "text/javascript">

var pw = "5";    // a string value, not a number
var x = "1e" + pw;  // concatenate strings
x = Number(x);  // make a number
alert (x); // 100000
x = x.toExponential();
alert (x);  // 1e+5

</script>

Quizmaster: A monocracy is a form of government in which how many people rule?
Contestant: Twelve.

[LXS]

Number object do the trick, I did not thought about this solution (to convert to a number object), because the type of 1e+24 is treated as a number, but simply 1e does not mean anything.
Thank you for fast-reply and for explanations!

[felgall]

Another alternative would be to use parseFloat.

var pw = 5;
alert (parseFloat('1e' + (pw)));

[LXS]

Again thanks a lot for your help!
There is the final result:

function getPrefix(value)
{
	var prefix="";
	var retVal = value;
	
	var i, j=0;
	var min, max, mul;
	
	// Table ordered by smallest submultiple to highest multiple
	var sTable=
	[
		// Metric submultiples
		"yocto","zepto","atto","femto","pico",
		"nano","micro","mili","centi","deci",
		// Metric multiples
		"deca","hecto","kilo","mega","giga",
		"tera","peta","exa","zetta","yotta"
	];
	
	for(i=-24; i<=24; i+=3)
	{
		min="1e"+(i.toString());
		min=Number(min);
		
		max="1e"+((i+3).toString());
		max=Number(max);
		
		if(i==0)
			i+=1;
		if(i>=0)
			mul="1e-"+(Math.abs(i).toString());
		else
			mul="1e"+(Math.abs(i).toString());	
		mul=Number(mul);
		
		if(value >= min && value < max)
		{
			prefix = sTable[j];
			retVal = value * mul;
			document.write("_____PICKED_____<br />");
			document.write("[I: "+i+"]<br />X: "+min+" -> Y: "+max+" -> Z: "+mul+"<br />");
			break;
		}
		else if(prefix == "" && i == 24)
			prefix = "prototype prefix";
		
		document.write("[I: "+i+"]<br />X: "+min+" -> Y: "+max+" -> Z: "+mul+"<br />");
		
		if(i >= -3 && i < 0 || i > 0 && i < 3)
			i -= 2;
		j++;
	}
	return [retVal,prefix];
}

var gp=getPrefix(0.1);
document.write("Value: " + gp[0] + " " + gp[1] + "<br />");

[Philip M]

Great, but you should get rid of document.write() which is obsolete. Remember that any document.write() statement that runs after the page finishes loading will create a new page and overwrite all of the content of the current page (including the Javascript which called it).