Original attempt to change invoice status from Javascript using the REST API

RevisedEntityStateUpdate.js

var setStateToIssued = function(invoiceId) {
    window.console.log('setStateToIssued(' + invoiceId + ')');
    invoiceId = invoiceId.replace(/[{}]/g, "");
    var url = Xrm.Page.context.getClientUrl() + "/api/data/v8.2/invoices(" + invoiceId + ")";
    var entity = {};
    //entity.statecode = 0; //commenting because we think setting state AND status causes workflows to fire twice
    entity.statuscode = 293750003; // Ready To Issue
    var req = new XMLHttpRequest();
    req.open("PATCH", url, true);
    req.setRequestHeader("OData-Version", "4.0");
    req.setRequestHeader("Accept", "application/json");
    req.setRequestHeader("Content-Type", "application/json; charset=utf-8");
    req.onreadystatechange = function () {
    if (this.readyState === 4) {
        req.onreadystatechange = null;
        if (this.status === 204) {
            //Success - No Return Data
            Xrm.Page.ui.close();
        } else {
            Xrm.Utility.alertDialog(this.statusText);
        }
    }};
    req.send(JSON.stringify(entity));
    };