Twilio Function template to support CORS

cors.js

exports.handler = function(context, event, callback) {
    const response = new Twilio.Response();
    response.appendHeader('Access-Control-Allow-Origin', '*');
    response.appendHeader('Access-Control-Allow-Methods', 'GET, OPTIONS, PUT, POST, DELETE');
    response.appendHeader('Access-Control-Allow-Headers', 'Content-Type');
    
    // check if the event has any data and if not assume this is the OPTIONS request
    if (Object.keys(event).length === 0) {
        response.setStatusCode(200);
        callback(null, response);
    } else {
        // call method here to do actual work
        method(context, event, callback, response);
    }
};