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Help with javascript tutorial

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Oct 13.2006

Going through a javascript tutorial and am stumped on how to make an example work. What is missing from this example?

Example: Using for each…in
The following snippet iterates over an array’s items, calculating their sum:

var sum = 0;
var arr = [5,7,9];
for each (var item in arr) {
sum += item;
}
print(sum);

//Source: [url]http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Statements:for_each…in[/url]

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JavaScript

5 Comments(s) ↴

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@felgallOct 13.2006 — nothing missing, you just have one word too many. The word [b]each[/b] is the cause of the problem, get rid of that word and you will have an inefficient but workable code. A more efficient way to do it would be:

var sum = 0;
var arr = [5,7,9];
for(var i = arr.length-1;i>=0;i--) {
sum += arr[i];
}
print(sum);

Of course how it displays the result depends on what you have in your print() function.
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@JMRKEROct 13.2006 — Fire this up:
[code=php]
<html>
<head>
<title>for each example</title>
</head>
<body>
<script type="text/javascript">
var sum = 0;
var arr = [5,7,9];
for (item=0; item<arr.length; item++) { sum += arr[item]; }
alert(sum);
</script>
</body>
</html>
[/code]
As far as I know there is not a 'for each' or 'foreach' command in javascript

and you would need to write a 'print()' function as well to make it work.

You may want to contact the tutorial people to see if they have an errata page (?)
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@jwgrafflinauthorOct 13.2006 — Thanks! With that information I was able to get this to work:

<script type="text/javascript">

var sum = 0;

var arr = [5,7,9];

for(var i = arr.length-1;i>=0;i--) {

sum += arr[i];

}

document.write(sum);

</script>



Guess I need to find a more current (or accurate) tutorial, huh?
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@JMRKEROct 13.2006 — With further testing, this seems to work as well:
[code=php]
<html>
<head>
<title>for each example</title>
</head>
<body>
<script type="text/javascript">
var sum = 0;
var arr = [5,7,9];
// for (item=0; item<arr.length; item++) { sum += arr[item]; }
msg = ''; for (item in arr) { sum += arr[item]; msg += item+' '; }
alert(sum+"n"+msg);
document.write(sum+"<br>"+msg);
</script>
</body>
</html>
[/code]
Interesting. I did not know you could use elements in array with (item in arr) construct.
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@jwgrafflinauthorOct 13.2006 — Thanks to you both for your prompt response. Been waiting over a week for a response from a similar forum.
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