What are the best practices for handling JSON data in PHP and JavaScript?

When handling JSON data in PHP and JavaScript, it is important to properly encode and decode the data to ensure compatibility between the two languages. In PHP, you can use the json_encode() function to convert an array or object to a JSON string, and json_decode() to convert a JSON string back to an array or object. In JavaScript, you can use JSON.stringify() to convert an object to a JSON string, and JSON.parse() to convert a JSON string back to an object.

// Encode an array to JSON in PHP
$data = array("name" => "John", "age" => 30);
$json_data = json_encode($data);
echo $json_data;
```

```javascript
// Decode a JSON string to an object in JavaScript
var json_data = '{"name": "John", "age": 30}';
var data = JSON.parse(json_data);
console.log(data);