whats wrong with this simple snippet (parsing string into array)?

Question

Assuming element with id 'id2' is a textarea with the following entries:

[email protected], [email protected], [email protected]

When I run this, I am getting values 0, 1 and 2 - why?

jQuery('#myid').submit(function() {
    var temp = jQuery('#id2').serializeArray();
    var email_arr = temp[0].value.split(',');
    for (e in email_arr)
        alert(e);
  return false;
});

Try alert(temp)ing, and see what you get :)

Patrick Perini
– Patrick Perini

2011-06-23 22:55:45 +00:00
Commented Jun 23, 2011 at 22:55 — Patrick Perini
– Patrick Perini, Commented Jun 23, 2011 at 22:55

Alexander Gessler · Accepted Answer · 2011-06-23 22:54:58Z

3

Because for ... in iterates keys, not values, so use alert(email_arr[e]) instead.

answered Jun 23, 2011 at 22:54

Alexander Gessler

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Comments

gilly3 · Accepted Answer · 2011-06-23 23:05:22Z

Because e contains the key of the object. To get the value, use email_arr[e].

Really, it's not wise to use for...in to iterate Arrays because it iterates, not just the items in the collection, but all the members of the Array including custom properties and methods. So, as soon as someone extends Array, you will get unexpected results in your for...in loop. For example, if you are using IE7 and you want to use Array.forEach() you'll have to extend Array as recommended by MDC. With Array extended, now each Array you create will have an extra property that will show up as you iterate using for...in.

Instead, use Array.forEach(). It's solves all kinds of problems that can crop up when looping through Arrays. This does what you are trying to do:

email_arr.forEach(function(email, index, list)
{
    alert(email);
});

fulmicoton · Accepted Answer · 2011-06-23 22:55:48Z

0

Unfortunately, in javascript, for ... in ... loop are not working the same way as in python. Your e variable is actually looping on the "index" (keys) of your array.

You should get the desired result by looking at email_arr[e].

answered Jun 23, 2011 at 22:55

fulmicoton

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2 Comments

nnnnnn Over a year ago

I wouldn't say that it is unfortunate, it's a simple way to get both the key and the value within the loop.

fulmicoton Over a year ago

well. I would. :D That's counterintuitive, because it does not match natural language.

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