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I want to convert a multi-dimensional PHP array to JavaScript and found this script in a post here;

<script type='text/javascript'>
<?php
$js_array = json_encode($php_array);
echo "var javascript_array = ". $js_array . ";\n";
?>
</script>

But the JS array remains empty. Is it because I have a multi-dimensional array?

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2  
Please show us a var_dump of your $php_array. – deceze Aug 1 '11 at 7:02
Is this dump ok?; array(20) { [0]=> array(6) { ["id"]=> string(3) "106" ["question"]=> string(34) "The capital of Bosnia Herzegovina." ["alternative1"]=> string(8) "Sarajevo" ["alternative2"]=> string(8) "Brussels" ["alternative3"]=> string(5) "Minsk" ["alternative4"]=> string(6) "Vienna" } – Fred Aug 1 '11 at 7:07
Double check that $php_array isn't empty. If its not, then $js_array will not be either. :) – daGrevis Aug 1 '11 at 7:07
Which version of PHP? json_encode() is available from 5.2 onward. Do you have error reporting on? – Juhana Aug 1 '11 at 7:20
The server has 5.2. I don't know if error reporting is on. – Fred Aug 1 '11 at 7:26

3 Answers

up vote 1 down vote accepted

Based on the comment you gave to one of the answers, are you sure $js_array is empty or are you just not decoding it? If you look at the generated JavaScript, do you see var javascript_array = ; or something else? Alternatively you could add alert( javascript_array ); to check.

EDIT: Since the variable is ok, you can now access the elements with javascript_array[0].id, javascript_array[0].question etc.

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In the generated JS is says;var javascript_array = [{"id":"152","question":"The capital of El Salvador.","alternative1":"San Salvador","alternative2":"Roseau","alternative3":"Havana","alternative4":null},{‌​" etc but alert( javascript_array ); gives [object Object], [object Object} etc – Fred Aug 1 '11 at 7:34
Looks like you're good to go, then. Is the problem that you don't know how to access the elements in the object? – Juhana Aug 1 '11 at 7:38
I would also be interested to know why the downvote? – Juhana Aug 1 '11 at 7:39
I guess that the problem then might be that I don't know how to access the elements in the object? Can you tell me how? I haven't downvoted anything. – Fred Aug 1 '11 at 7:43
@Fred: There is plenty of documentation: developer.mozilla.org/en/JavaScript/Guide/Working_with_Objects – Felix Kling Aug 1 '11 at 7:52
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up vote -2 down vote

If $php_array isn't empty, try to...

var javascript_array = <?php echo $js_array; ?>;

...instead of:

echo "var javascript_array = ". $js_array . ";\n";

Hope it helps! :)

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Still the same problem.. I'm using this to check javascript array; – Fred Aug 1 '11 at 7:18
1) Doesn't respond to his problem and 2) wouldn't make any difference if it did. – Juhana Aug 1 '11 at 7:19
for(var i=0;i<javascript_array.length;i++){ document.write("<b>javascript_array["+i+"] is </b>=>"+javascript_array[i]+"<br>"); } alert (javascript_array[3][4]); it just says 'jsquestions[0] is =>[object Object]' and 'Undefined' – Fred Aug 1 '11 at 7:20
@Fred: So why do you say javascript_array is empty? Obviously javascript_array[0] has a value. You said yourself that it is a multidimensional array (actually it is an array of objects). The array contains one object at index 0. Hence javascript_array[3][4] does not exist. If you, e.g. want the id, you can get it via javascript_array[0].id. – Felix Kling Aug 1 '11 at 7:50
up vote -2 down vote

You probably have to eval that json in order for it to be more than just a string in your JavaScript code.

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I'm totally new at this. How do I 'eval' it? – Fred Aug 1 '11 at 7:23
There is JavaScript's function eval(), but its not related. – daGrevis Aug 1 '11 at 7:35

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