(ArcGIS API for JavaScript) Sample of getting user items and accessing secured layers without user authentication.

Sample.js

require(["esri/map",
        "esri/arcgis/Portal",
        "esri/urlUtils",
        "esri/request",
        "esri/config",
        "dojo/domReady!"
], function (Map, arcgisPortal,urlUtils, Request, Config) {

    //Push the server to the cors array to avoid CORS related errors.
    Config.defaults.io.corsEnabledServers.push("FQDN of server");

    var map = new Map("map", {
        center: [-118, 34.5],
        zoom: 8,
        basemap: "topo"
    });

    //Add a proxy rule, to send requests through the proxy
    urlUtils.addProxyRule({
        urlPrefix: "FQDN of the web server which the proxy is on",
        proxyUrl: "https://FQDN/DotNet/proxy.ashx"
      });

    var urls = [
        "https://FQDN/portal/sharing/rest/content/users/admin", //See what files are associated with a certain user from portal.
        "https://FQDN/server/rest/services/Hosted/Cites/FeatureServer" //Access a secured layer from portal.
    ];


    //Send a request using the request module
    urls.forEach((element) =>{
        var request = new Request({
                url: element,
                content: {f:"pjson"},
                handleAs: "json"
        });
        request.then((response) => { console.log(response);});
    });
});

This is a sample using the proxy to access items and secured layers from a portal. The use of a proxy allows you to store credentials in the proxy config so that the end user will not have to log in.

Additional information to be aware of:

• Documentation of using the REST API for managing portals can be accessed here (https://developers.arcgis.com/rest/users-groups-and-items/working-with-users-groups-and-items.htm
• A Proxy is needed for this to work. Make sure the proxy is set up correctly by following the documentation specified here (https://github.com/Esri/resource-proxy)