Multidimensional arrays in Javascript

Posted on 2007-08-02
Medium Priority
Last Modified: 2008-01-09
I've posted some code for a simple form.  I have commented out the part of the function that isn't working as I would expect.

When a 'country' is selected from the drop-down menu, the corresponding 'country code' is populated in text fields of the form.

This works (form rows '1' and '2'):
  document.forms.myForm.country0.value = countryCode

This does not work (form rows '3' and '4'):
  document.forms.myForm.people[0][country].value = countryCode

I'd prefer to reference the form elements as in rows 3 and 4 but am uncertain how to reference multidimensional arrays in Javascript.

How should I go about this?

<title>People :: Names and Countries</title>
<script type="text/javascript">
  var country = "";
  function addCountry(countryCode) {

    // This works -- 'country code' IS ADDED to rows 1 and 2
    document.forms.myForm.country0.value = countryCode
    document.forms.myForm.country1.value = countryCode
    // This doesn't work -- 'country code' IS NOT ADDED to rows 3 and 4
    // document.forms.myForm.people[0][country].value = countryCode
    // document.forms.myForm.people[1][country].value = countryCode

<form name="myForm" method="post" action="processForm.php">
  <select name="countryCode" onchange="addCountry(this.value);">
    <option value="" selected>(Select COUNTRY)</option>
    <option value="CAN">Canada</option>
    <option value="FRA">France</option>
    <option value="UK">United Kingdom</option>

1. NAME:<input type=text name=name0> COUNTRY:<input type=text name=country0><br />
2. NAME:<input type=text name=name1> COUNTRY:<input type=text name=country1><br />

3. NAME:<input type=text name=people[0][name]> COUNTRY:<input type=text name=people[0][country]><br />
4. NAME:<input type=text name=people[1][name]> COUNTRY:<input type=text name=people[1][country]><br />
Question by:speyfisher
  • 3
LVL 54

Accepted Solution

b0lsc0tt earned 2000 total points
ID: 19622113
I don't see an array, or at least a Javascript array.  Fields 3 and 4 have a name that uses a bracket but that doesn't make it a Javascript array.  The brackets may cause problems for Javascript to access it but try ...

    document.forms.myForm.elements["people[0][country]"].value = countryCode
    document.forms.myForm.elements["people[1][country]"].value = countryCode

Let me know how that works or if you get an error.

LVL 54

Expert Comment

ID: 19622116
If that doesn't work then can you either put the name value in quotes (e.g. name="people[0][name]") or use a different name (one without brackets)?


Author Comment

ID: 19622199
The first comment got it going by using '.elements[]'

    document.forms.myForm.elements["people[0][country]"].value = countryCode

The second comment-- (var name="...)  value in quotes didn't do it.  Using a different name without brackets worked fine in the example but I'd prefer the POST data sent to the php script be accessible something like: $country = $_POST['people'][$i]['country'];

Thanks bol!
LVL 54

Expert Comment

ID: 19622336
Your welcome!  I'm glad the first worked then.  I have had issues before but I was pretty confident elements[] would be a way to do it.

Thanks for the grade, the points and the fun question.


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