无法在javascript中回显PHP变量

I have a PHP variable which contains a JSON object in string format.

<?php
$url = "http://ip-api.com/json";
$phpObj = file_get_contents($url);
?>

Javascript:

<script>
var obj = "<?php echo $phpObj; ?>";
</script>

When I try to echo a PHP variable in javascript, I get the following error:

Uncaught SyntaxError: Invalid or unexpected token.

I've tried using json_encode, but it gives me the same error.

No need to use the quotes ("s) and json_encode as it is already a JSON object. Try

var obj = <?php echo $phpObj; ?>;

When I ma fetching the data and try -

<?php
$phpObj = file_get_contents("http://ip-api.com/json");
?>

<script>
var obj = <?php echo $phpObj; ?>;
console.log(obj);
</script>

I am getting -

{as: "AS45194 Syscon Infoway Pvt. Ltd.", city: "Thane", country: "India", countryCode: "IN", isp: "Syscon Infoway Pvt.", …}

in the console.

Passing simple arrays or arrays of objects between PHP and JavaScript can be done through json_encode and json_decode respectively. For instance, in your case, I can do the following

<?php
  $url = "http://ip-api.com/json";
  $phpObj = file_get_contents($url);
?>
 <script>
  var obj = <?php echo $phpObj; ?>;
 </script>

Since the data fetched is JSON.

However, this fully depends on your application. If $phpObj = file_get_contents($url); returns json then I will simply do the following

<script>
  var obj = <?php echo $phpObj; ?>;
 </script>

If it's an object that is returned($phpObj), then I will, first of all, convert the object to an array then parse it into JSON format then echo it to JavaScript as shown below

<script>
  var obj = <?php echo json_encode((array)$phpObj); ?>;
 </script>

If it's an array that is returned, then I will parse the variable to JSON format then echo it to JavaScript as shown below

<script>
  var obj = <?php echo json_encode($phpObj); ?>;
 </script>

For the case of json_decode, if for instance, you want to use the value returned by file_get_contents($url); and assuming this returns JSON, you can convert the JSON to a PHP array or a PHP object as shown below,

$data_obj = json_decode($phpObj); //Return object not array
$data_arr = json_decode($phpObj,true); //Return array not object