XMLHttpRequest cannot load http://myApiUrl/login. No
'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'null' is therefore not allowed access.

$.ajax({
    type: "POST",
    dataType: 'text',
    url: api,
    username: 'user',
    password: 'pass',
    crossDomain : true,
    xhrFields: {
        withCredentials: true
    }
})
    .done(function( data ) {
        console.log("done");
    })
    .fail( function(xhr, textStatus, errorThrown) {
        alert(xhr.responseText);
        alert(textStatus);
    });

chrome.exe --user-data-dir="C:/Chrome dev session" --disable-web-security

$.ajax({
  type: "POST",
  dataType: 'jsonp',
  ...... etc ....

<?php header('Access-Control-Allow-Origin: *'); ?>

// The following property can be used to configure cross-origin resource sharing
// in the HTTP nodes.
// See https://github.com/troygoode/node-cors#configuration-options for
// details on its contents. The following is a basic permissive set of options:
httpNodeCors: {
 origin: "*",
 methods: "GET,PUT,POST,DELETE"
},

app.use(function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    next();
});

<cffunction name="optionsMethod" access="remote" output="false" returntype="any" httpmethod="OPTIONS" description="Method to respond to AngularJS trial call">
    <cfheader name="Access-Control-Allow-Headers" value="Content-Type,x-requested-with,Authorization,Access-Control-Allow-Origin">
    <cfheader name="Access-Control-Allow-Methods" value="GET,OPTIONS">
    <cfheader name="Access-Control-Allow-Origin" value="*">
    <cfheader name="Access-Control-Max-Age" value="360">
</cffunction>

Spark.get("/someRestCallToSpark", (req, res) -> {
    res.header("Access-Control-Allow-Origin", "*"); //important, otherwise its not working
    return "some text";
 });

Ext.Ajax.request({
    url: "http://localhost:4567/someRestCallToSpark",
    useDefaultXhrHeader: false, //important, otherwise its not working
    success: function(response, opts) {console.log("success")},
    failure: function(response, opts) {console.log("failure")}
});

using (DBContext db = new DBContext())
{
    return db.Customers.Select(x => new
    {
        Name = x.Name,
        CustomerId = x.CustomerId,
    });
}

using (DBContext db = new DBContext())
{
    return db.Customers.Select(x => new
    {
        Name = x.Name,
        CustomerId = x.CustomerId,
    }).ToList();
}

@GET
    @Path("{id}")
    public Response getEventData(@PathParam("id") String id) throws FileNotFoundException {
        InputStream inputStream = getClass().getClassLoader().getResourceAsStream("/eventdata/" + id + ".json");
        JsonReader jsonReader = Json.createReader(inputStream);
        return Response.ok(jsonReader.readObject()).header("Access-Control-Allow-Origin", "*").build();
    }

var yql_url = 'https://query.yahooapis.com/v1/public/yql';
var url = 'your api url';

$.ajax({
'url': yql_url,
'data': {
'q': 'SELECT * FROM json WHERE url="'+url+'"',
'format': 'json',
'jsonCompat': 'new',
 },
'dataType': 'jsonp',
'success': function(response) {
 console.log(response);
},
});

<httpProtocol>
    <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
    </customHeaders>
</httpProtocol>

$.ajax({
    url: 'http://mysite.microsoft.sample.xyz.com/api/mycall',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded'
    },
    type: "POST", /* or type:"GET" or type:"PUT" */
    dataType: "json",
    data: {
    },
    success: function (result) {
        console.log(result);
    },
    error: function () {
        console.log("error");
    }
});

<filter>
    <filter-name>CORS</filter-name>
    <filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>CORS</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

/Applications/Google Chrome.app/Contents/MacOS/Google Chrome --allow-file-access-from-files