Cors issues using sharepoint - asp.net

Question

i'm trying to query using REST API (sharepoint) and get some results.
this is where i've started
https://www.slideshare.net/CoreyRoth/fives-ways-to-query-share-point-2013-search-sharepoint-summit-toronto-2013, slide 31
this is what i have
document.getElementById("restApi")
.addEventListener("click", restApi, false);
function restApi() {
var queryUrl = "https://myAppDomain.org/_api/search/query?querytext='" + $("#restSearch").val() + "'";
$.ajax({
type: "GET",
url: queryUrl,
xhrFields: {
withCredentials: true
},
headers: {
"Accept": "application/json; odata=verbose"
},
success: function (data) {
var results = data.d.query.PrimaryQueryResult.RelevantResults.Table.Rows.results;
},
error: function (error) {
}
});
}
this is the problem.
XMLHttpRequest cannot load "https://myAppDomain.org/_api/search/query?querytext=x" No 'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'http://localhost:63734' is therefore not allowed
access.
and another way i've tried providing password and username
headers: {
"Accept": "application/json; odata=verbose",
"password": "my password",
"username": "my account name"
},
for which i get
XMLHttpRequest cannot load
https://myAppDomain.org/_api/search/query?querytext=x. 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:63734' is therefore not allowed
access. The response had HTTP status code 401.
I'm using .net webApi, for which i've installed the cors packages, configuration
// Enabled cors
config.EnableCors(new EnableCorsAttribute("*", "*", "*") { SupportsCredentials = true });
The app are internal and i'm using windows credentials pass and account name.
So why am i getting this error, what do i do wrong?, i've searched and tried other solutions but always get the same problem related to
No 'Access-Control-Allow-Origin' header is present on the requested

Answer 1

Open IIS
Go to Sites and find your Sharepoint site
Right-click -> Explore
Open web.config
Add the following code inside system.webServer node
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
</customHeaders>
</httpProtocol>
</system.webServer>
</configuration>
Save and exit

Answer 2

I've managed to solve my issue (partially, because i would have wanted to use CSOM rather then REST API on client side) by allowing cross domain calls from my application, directly to the application(sharepoint app) for which i made the request.
So in the requested app i've added the following file :
web.config
in section :
system.webserver/httpprotocol/customheaders
content :
<add name="Access-Control-Allow-Origin" value="https://myApplicationDomain.zzz" />
<add name="Access-Control-Allow-Methods" value="GET,PUT,POST,DELETE,OPTIONS" />
<add name="Access-Control-Allow-Headers" value="Content-Type" />
<add name="Access-Control-Allow-Credentials" value="true" />

Answer 3

If the server is being developed by you
Have you put the "Access-Control-Allow-Origin: localhost" in your .htaccess or in your webserver configuration?
You can, also, add that header in your response from the server.