A simple (and not perfect) AWS lambda function to work around the ignored `Access-Control-Allow-Origin: *` wildcard in Google Chrome.

corsDummyLambda.js

exports.handler = (event, context, callback) => {
    // Checking properties case insensitively, might be a better solution but this one works
    // => https://stackoverflow.com/a/5833423/519376
    Object.prototype.hasOwnPropertyCI = function(prop) {
       return Object.keys(this)
              .filter(function (v) {
                 return v.toLowerCase() === prop.toLowerCase();
               }).length > 0;
    };
    Object.prototype.getPropertyCI = function(prop) {
       return this[Object.keys(this)
              .filter(function (v) {
                 return v.toLowerCase() === prop.toLowerCase();
               })[0]]; // Be carefull here!
    };
    var headers = {};
    if(event.headers.hasOwnPropertyCI("access-control-request-headers"))
        headers["Access-Control-Allow-Headers"] = event.headers.getPropertyCI('access-control-request-headers');
    if(event.headers.hasOwnPropertyCI("access-control-request-method"))
        headers["Access-Control-Allow-Methods"] = event.headers.getPropertyCI('access-control-request-method');
    if(event.headers.hasOwnPropertyCI("origin"))
        headers["Access-Control-Allow-Origin"] = event.headers.getPropertyCI('origin');
    //console.log(headers);
    var response = {
            statusCode: 204,
            headers: headers
        };

    callback(null, response);
};