Issues with cross-domain requests

My front-end code is like this,
The backstage is written in PHP,

  , ' returndesc ' = ' success ');        Returns the underlying data function __construct () {$this->return[' servertime ') =time ();        Log::record (' Incoming parameters: '. Var_export ($_request, True), Log::D ebug);        $this->params = @json_decode (Base64_decode ("I (' Post.params '), true), true);            if (! $this->params) {$this->return[' returncode ') = 100;            $this->return[' returndesc '] = ' sign failed! ';        $this->responsejson ();            }else if (C (' key ')! = $this->params[' key ') {$this->return[' returncode '] = 100;            $this->return[' returndesc '] = ' sign failed! ';            $this->return[' returnalert '] = ' key is incorrect! ';        $this->responsejson ();        }/* * Check how the interface is passed in */Public function Checkpublicparams ($interfaces) {$pass = false;        $this->return[' returncode '] = 100; if (! I (' post. '))        {$this->return[' returndesc ') = ' request method error '; } else if (! I (' Post.method ') | | ! I (' Post.parAMs ') {$this->return[' returndesc ') = ' interface parameter error ';        } else if (!array_key_exists (I (' Post.method '), $interfaces)) {$this->return[' returndesc '] = ' interface name error ';            } else {$this->return[' returncode ') = 200;        $pass = true;    } return $pass;    } protected function Responsejson () {exit (Json_encode ($this->return)); }}

The unchanged state is the return authentication failure
"{" ReturnCode ":" Returndesc ":" Sign failed! "," Servertime ": 1476799012}"
I found a way to change it on the Internet.

But I don't know how to modify it.

