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Test for array element defined …

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Feb 15.2008

Is there a way to tell if an array element does or does not have a value associated with it?

In PERL I would be able to:
if (!defined($arr[p])) { $arr[p] = 0; }

Is there a similar assignment with JS? ?

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JavaScript

5 Comments(s) ↴

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@Wisest_GuyFeb 15.2008 — [CODE]if (typeof arr[index] == "undefined"){arr[index] = 0;}[/CODE]
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@mrhooFeb 15.2008 — if(arr[i]===undefined) arr[i]=0;
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@JMRKERauthorFeb 15.2008 — Thanks to you both.

I'll give them a try.
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@toicontienFeb 15.2008 — Using the typeof function has one small annoyance. Internet Explorer 5 doesn't return "undefined" for undefined variables. If IE5 is not a concern, then use the typeof method.
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@JMRKERauthorFeb 15.2008 — 'toicontien':

Thanks for the 'heads-up".

I use FF mostly, but I know my students use anything they can get their hands on.

Saves me a lot of head scratching when things don't go as expected.
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