<?php var_dump($myArray); ?>

array (size=4)
  'id' => string '162' (length=3)
  'content' => string 'Test content' (length=12)
  'children' =>
    array (size=16)
      0 =>
        array (size=4)
          'id' => string '29208' (length=5)
          'content' => string 'Test content 1' (length=14)
          'children' =>
            array (size=3)
              ...
      1 =>
        array (size=4)
          'id' => string '29215' (length=5)
          'content' => string 'Test content 2' (length=14)
          'children' =>
            array (size=1)
              ...
      2 =>
        array (size=3)
          'id' => string '29220' (length=5)
          'content' => string 'Test Content 3' (length=14)

<script type="text/javascript">
var myVar = JSON.parse('<?php json_encode($myArray) ?>');
</script>

Uncaught SyntaxError: Unexpected end of input

<script type="text/javascript">
var x = '{"id":123,"content":"This is a test content"}';
var myVar = JSON.parse(x);
console.log(myVar);
</script>

Object
    content: "This is a test content"
    id: 123

<?php json_encode($myArray) ?>

<?php echo json_encode($myArray) ?>