Iterating over PHP array to create Javascript array with PHP foreach

Question

I'm having a bit of trouble with an annoying ',' during the iteration of a PHP array to produce a Javascript array. Essentially, what I have is this:

<?php
  $array = array(StdObject,StdObject,StdObject);
?>

//later that page...in JavaScript

var list = [
<?php foreach($array as $value):?>
  '<?=$value->some_letter_field?>',
<?endforeach;?>
];

Unfortunatly, what this code does is produce output that looks like this:

var list = ['a','b','c',];

Notice that extra comma in the JavaScript array? This is causing some issues. How would I go about re-writing this PHP snippet so that extra comma doesn't get printed, producing a properly formatted JavaScript array?

The expected output should be:

var list = ['a','b','c'];

I appreciate your help in advance.

Paolo Bergantino · Accepted Answer · 2012-12-11 16:38:03Z

9

You don't need to do this yourself, PHP has a function called json_encode that does what you want. If for some reason you don't have PHP 5.2.0, there are a lot of implementations in the comments of that page to get around that.

answered Dec 11, 2012 at 16:38

Paolo Bergantino

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1 Comment

Sinmok Over a year ago

My apologies. I should have made the question clearer. The PHP array actually contains a list of stdObjects. Using json_encode() doesn't quite work.

Alexander Taver · Accepted Answer · 2012-12-11 16:46:49Z

5

Use implode() to glue up array elements. It will take care about commas

//later that page..in JavaScript

var list = ['<?=implode("', '", $array)?>'];

edited Dec 11, 2012 at 16:46

answered Dec 11, 2012 at 16:39

Alexander Taver

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1 Comment

Sami Over a year ago

I like this solution very much, but it require that the array is flattened before.

Alvaro · Accepted Answer · 2012-12-11 16:40:06Z

1

You can use this to generate the json array:

$list = json_encode($array);

And then read it in Javascript:

var list = <?=$list?>

answered Dec 11, 2012 at 16:40

Alvaro

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1 Comment

Kelly Copley Over a year ago

no need for the php tag its a string that is output as javascript to the browser.

Ivan Hušnjak · Accepted Answer · 2012-12-11 16:55:42Z

1

This will do the trick:

<?php 
$filtered = array();
foreach($array as $value) {
    $filtered[] = $value->some_letter_field;
}
echo 'var list = ' . json_encode($filtered);
?>

answered Dec 11, 2012 at 16:55

Ivan Hušnjak

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1 Comment

Jeffrey Kastner Over a year ago

This worked for me, but it is missing a ; in echo 'var list = '.json_encode($filtered).';';

Vladimir Minakov · Accepted Answer · 2012-12-11 16:43:15Z

0

How about converting array to a valid JSON object?

var list = JSON.parse("<?php echo json_encode($array); ?>");

Anyway, do you really need to generate JS code on the fly? Isn't there another way to complete your task? JS generation is often considered a hack, and it can be avoided easily in many cases.

answered Dec 11, 2012 at 16:43

Vladimir Minakov

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4 Comments

Sinmok Over a year ago

The array is used to draw charts in JS where the values are being pulled from the DB.

Kelly Copley Over a year ago

why would you JSON.parse this when its going to be run in the browser anyway?

Kelly Copley Over a year ago

@Sinmok if these values are pulled from a DB just make sure you are running proper sanitization on the values

Vladimir Minakov Over a year ago

@Sinmok true, there's no real need to parse it, if the JSON objects contains only simple values. However, quite often you want to do additional formatting for complex types, like convert date strings to Date objects. JSON.parse() allows you to specify that formatting callback. But if it's just a bunch of strings or numbers, you are right, .parse() can be omitted

Dan H · Accepted Answer · 2012-12-11 16:58:16Z

-1

If you insist in keeping your current code for whatever reason, just:

var list = [
<?php foreach($array as $value): ?>
  $output[] = "'".$value->some_letter_field."'";
<?php endforeach; ?>
  echo implode(',', $output);
];

answered Dec 11, 2012 at 16:58

Dan H

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