Passing optional array from PHP to jQuery

Question

I have a problem if this optional array is empty:

<script>
    var parsedArray = JSON.parse('<?php echo json_encode($myArray); ?>');
    console.log(parsedArray );
</script>

All is fine if array is NOT empty, but the problem comes if there are no values in array;

Uncaught SyntaxError: Unexpected token A in JSON at position 0

Console.log just spits Array out if array is empty.

I want to learn how is this done properly. How to pass an empty array to jQuery so I can run myArray.length function on it for example and so that it returns 0 if it is empty.

Normally if $myArray is an empty array() json_encode should return [] so I'm not sure where the syntax error is coming from. What does the response from json_encode($myArray); look like if empty or rather what is $myArray looking like? — empiric
– empiric, Commented Mar 23, 2018 at 14:51

Terry · Accepted Answer · 2018-03-23 14:53:39Z

2

You can use tenary operators when echoing out your $myArray. If it is empty, you can simply pass null to JSON.parse instead, i.e.:

var parsedArray = JSON.parse('<?php echo !empty($myArray) ? json_encode($myArray) : "null"; ?>');
console.log(parsedArray);

edited Mar 23, 2018 at 14:53

answered Mar 23, 2018 at 14:47

Terry

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Praveen Kumar Purushothaman · Accepted Answer · 2018-03-23 14:49:15Z

1

With the above answer, I would also add the 's to the PHP:

var parsedArray = JSON.parse(<?php echo !empty($myArray) ? "'" . json_encode($myArray) . "'" : "null"; ?>);
console.log(parsedArray);

Because we wouldn't use null as 'null'.

answered Mar 23, 2018 at 14:49

Praveen Kumar Purushothaman

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Racil Hilan · Accepted Answer · 2018-03-23 14:50:31Z

1

You can check $myArray when echoing it out and do something if it is empty. What to do depends on how you will be using parsedArray afterwords. You can pass an empty array []:

var parsedArray = JSON.parse('<?php echo !empty($myArray)? json_encode($myArray) : "[]"; ?>');
console.log(parsedArray);

answered Mar 23, 2018 at 14:50

Racil Hilan

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lewis4u · Accepted Answer · 2018-03-23 14:56:02Z

0

I think it is not necessary to do the if statement i figured it out and my problem was that I did the json_encode($myArray) in PHP code and then JSON.parse in javascript

it works like this without problems:

in PHP just declare the array

$myArray = [];

and in php file under script spit it out like this:

var myArray = <?= json_encode($myArray) ?>;

And now even if array is empty it will spit out [];

answered Mar 23, 2018 at 14:56

lewis4u

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