Sum and Average Calculator

JavaScript
1

Hi,

I’m very new to Javascript and I’ve been trying to complete a ‘simple’ assignment for a few weeks now. Just wondering if anyone can help explain to me what is wrong with my code:

<html>

<head>

<title>Aggregates</title>

<script type=“text/javascript”>

var numbers = new Array();

function insert(input) 
{
	var newNumber = input.value;
	input.value = "";
	numbers[numbers.length] = newNumber;
}

function show() 
{
	var string="";
	for(i = 0; i &lt; numbers.length; i++)
	string = string + numbers[i]+"\

";
document.getElementById(“e”).value = string;
}

function sum()
{ 
	if (numbers.length == 0) return 0;
	for (var i=0,total=0; i &lt; numbers.length; i++) 
	total += numbers[i];
	document.getElementById("Sum").value = m;
	return total;
}

function mean()
{
	var m = numbers.length == 0 ? 0 : sum(null)/numbers.length;
	document.getElementById("Mean").value = m;
	return m;
}

function resetNumbers()
{
	numbers = new Array();
}

</script>

</head>

<body>
<h1>Aggregates</h1>
<h3>Add as many numbers as you like </br> to the list, then click Calculate.</h3>
<form id=“formtext” form name=“formtext”>
<input type=“text” name=“name” value=“”></input>
<input type=“button” value=“Add to list” onClick=“insert(document.formtext.name);show();”></input></br>

	&lt;textarea name="txt" id="e" rows="10" &gt;&lt;/textarea&gt; &lt;/br&gt;
	&lt;input type="button" value="Calculate" onClick="sum();mean()"&gt;&lt;/input&gt; 
	&lt;input type="button" value="Reset" onClick="resetNumbers();form.reset()"&gt;&lt;/input&gt;

	&lt;h4&gt;Total (Sum):&lt;/h4&gt;
	&lt;input type="text" id="Sum" value="0"&gt;&lt;/input&gt;&lt;/br&gt;

	&lt;h4&gt;Average:&lt;/h4&gt;
	&lt;input type="text" id="Mean" value="0"&gt;&lt;/input&gt;&lt;/br&gt;


&lt;/form&gt;

</body>

</html>

On opening it in IE is tells me ‘m’ is undefined, in function sum() and function mean(). I got most of the code from a previous thread http://www.sitepoint.com/forums/showthread.php?746348-sum-mean from someone else doing the same assignment and someone posted the answer…which doesn’t work. I have been googling and found a few different ways of finding the sum and average of an array, but each way I’ve tried is not working. I tried merging the two functions together into function sumAverage:

function SumAverage()
{
var count
var Sum = 0
var Average
var result

		// Find the lowest & highest
		for (var i = 0; i &lt; scores.length; i++)
			Sum=Sum + scores[i]
		Average = Sum/scores.length

but struggle how to correctly assignment the answer to the correct place using ‘document.getElementById’.

Any help much appreciated, it’s driving me crazy

Simon

2

On opening it in IE is tells me ‘m’ is undefined, in function sum() and function mean()

That error msg is telling you that you haven’t assigned a value to m yet before trying to assign its value to another variable.

function sum()
            {
                if (numbers.length == 0) return 0;
                for (var i=0,total=0; i < numbers.length; i++)
                    total += numbers[i];
                [COLOR=#ff0000][B]document.getElementById("Sum").value = m;[/B][/COLOR]
                return total;
            }

What is the purpose of the m variable and where have you assigned a value to m ?

3

Hi,

Thanks for the reply, I’ve changed the m in function sum() to total:
function sum()
{
if (numbers.length == 0) return 0;
for (var i=0,total=0; i < numbers.length; i++)
total += parseInt(numbers[i]);
document.getElementById(“Sum”).value = total;
return total;
}
and it seems to work now, I also changed the numbers[i] to an integer. Just have to add comments, double check the code and add NaN and hopefully it’s finished.