Q:

$http.get() Error ‘Access-Control-Allow-Origin’

I have to work with the API rest but i have this error every time whenever do?
Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8100' is therefore not allowed access.
$scope.submit = function(login, password){
url = 'http://x.x.x.x:x/x/x/x/x/'+login+'?password='+password;
console.log(url);
instanceId = '1';
tokenId = '';
userId = '';
$http.get(url, {
      headers: {
        'Accept': 'application/json',
        'Context': 'instance='+tokenId+';token='+tokenId+';user='+userId
      }
  })
  .success(function(data){
    $scope.firstName = data.user.firstName;
    $scope.lastName = data.user.lastName;
    $scope.profession = data.user.mission;

    userId = data.user.id;*/
    localStorage.setItem("userId", JSON.stringify(userId));
    $location.path('app/home/');
  })
  .error(function(data, status){
    console.log(data + "-" + status);
    alert(status);
});

A:

CORS is only an issue when running your app in development mode with ionic serve or ionic run/emulate -l, and not when running as a mobile app packaged with Cordova, a simple option is to just disable CORS altogether for local development. If you use Chrome for debugging, there's a plugin called Allow-Control-Allow-Origin: * that lets you disable CORS.
Or if you want to solve this issue, there has two ways:

The first, and easier, solution is to just allow all origins from your API endpoint. The disadvantage is that we can not always control the endpoint we are accessing.
Fortunately, we have second way: Ionic CLI proxy server, ionic has supplied an awesome blog about this, please refer to http://blog.ionic.io/handling-cors-issues-in-ionic/.

Hope this will help, regard.

