Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

drupal_json_encode() has been moved to \Drupal\Component\Serialization\Json::encode() and
drupal_json_decode() has been moved to \Drupal\Component\Serialization\Json::decode().

Drupal 7:

$json = drupal_json_encode($data);
$data = drupal_json_decode($json);

Drupal 8:

use Drupal\Component\Serialization\Json;
$json = Json::encode($data);
$data = Json::decode($json);
Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done