Assign null php variable to javascript

Question

How can I pass null PHP variable to javascript?

My code is as:

<?php

$size = null;

<< Call Rest API >>
if (<some_condition_here>) {
    $size = <rest_api_value>;
}
echo "<input name='diff_size' id='diff_limit' type='test' value='$size' />";

<script>
var initial_value = $size

function checkIfChanged() {
    if ($('diff_size').val() == initial_val )
    {
        return false;
    }
    return true;
}

</script>
?>

<< On submit javascript function is called >>

Error message:

Uncaught SyntaxError: Unexpected token ;

var initial_value = ;

You want to wrap $size in quotes otherwise the JavaScript might get parsing errors. — Chris Hemmens
– Chris Hemmens, Commented Sep 16, 2019 at 20:08

Chris Hemmens · Accepted Answer · 2019-09-16 20:10:01Z

2

<?php

$size = null;

<< Call Rest API >>
if (<some_condition_here>) {
    $size = <rest_api_value>;
}
echo "<input name='diff_size' id='diff_limit' type='test' value='$size' />";
?>
<script>
var initial_value = '<?= $size ?>';

function checkIfChanged() {
    if ($('diff_size').val() == initial_val )
    {
        return false;
    }
    return true;
}

</script>

answered Sep 16, 2019 at 20:10

Chris Hemmens

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