Using drawing tool of ArcGIS

I am discovering Drawing tool of ArcGIS. The code of a widget looks as follows:

<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <meta name="viewport" content="width=device-width,user-scalable=no">

    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
    <title>Maps Toolbar</title>

    <link rel="stylesheet" href="https://js.arcgis.com/3.20/dijit/themes/nihilo/nihilo.css">
    <link rel="stylesheet" href="https://js.arcgis.com/3.20/esri/css/esri.css">
    <style>
      html, body, #mainWindow {
        font-family: sans-serif; 
        height: 100%; 
        width: 100%; 
      }
      html, body {
        margin: 0; 
        padding: 0;
      }
      #header {
        height: 80px; 
        overflow: auto;
        padding: 0.5em;
      }
    </style>

    <script src="https://js.arcgis.com/3.20/"></script>
    <script>
      var map, toolbar, symbol, geomTask;

      require([
        "esri/map", 
        "esri/toolbars/draw",
        "esri/graphic",

        "esri/symbols/SimpleMarkerSymbol",
        "esri/symbols/SimpleLineSymbol",
        "esri/symbols/SimpleFillSymbol",

        "dojo/parser", "dijit/registry",

        "dijit/layout/BorderContainer", "dijit/layout/ContentPane", 
        "dijit/form/Button", "dijit/WidgetSet", "dojo/domReady!"
      ], function(
        Map, Draw, Graphic,
        SimpleMarkerSymbol, SimpleLineSymbol, SimpleFillSymbol,
        parser, registry
      ) {
        parser.parse();

        map = new Map("map", {
          basemap: "streets",
          center: [-15.469, 36.428],
          zoom: 3
        });

        map.on("load", createToolbar);

        // loop through all dijits, connect onClick event
        // listeners for buttons to activate drawing tools
        registry.forEach(function(d) {
          // d is a reference to a dijit
          // could be a layout container or a button
          if ( d.declaredClass === "dijit.form.Button" ) {
            d.on("click", activateTool);
          }
        });

        function activateTool() {
          var tool = this.label.toUpperCase().replace(/ /g, "_");
          toolbar.activate(Draw[tool]);
          map.hideZoomSlider();
        }

        function createToolbar(themap) {
          toolbar = new Draw(map);
          toolbar.on("draw-end", addToMap);
        }

        function addToMap(evt) {
          var symbol;
          toolbar.deactivate();
          map.showZoomSlider();
          switch (evt.geometry.type) {
            case "point":
            case "multipoint":
              symbol = new SimpleMarkerSymbol();
              break;
            case "polyline":
              symbol = new SimpleLineSymbol();
              break;
            default:
              symbol = new SimpleFillSymbol();
              break;
          }
          var graphic = new Graphic(evt.geometry, symbol);
          map.graphics.add(graphic);
        }
      });
    </script>
  </head>
  <body class="nihilo">

  <div id="mainWindow" data-dojo-type="dijit/layout/BorderContainer" data-dojo-props="design:'headline'">
    <div id="header" data-dojo-type="dijit/layout/ContentPane" data-dojo-props="region:'top'">
      <span>Draw:<br /></span>
      <button data-dojo-type="dijit/form/Button">Point</button>
      <button data-dojo-type="dijit/form/Button">Multi Point</button>
      <button data-dojo-type="dijit/form/Button">Line</button>
      <button data-dojo-type="dijit/form/Button">Polyline</button>
      <button data-dojo-type="dijit/form/Button">Polygon</button>
      <button data-dojo-type="dijit/form/Button">Freehand Polyline</button>
      <button data-dojo-type="dijit/form/Button">Freehand Polygon</button>

      <button data-dojo-type="dijit/form/Button">Arrow</button>
      <button data-dojo-type="dijit/form/Button">Triangle</button>
      <button data-dojo-type="dijit/form/Button">Circle</button>
      <button data-dojo-type="dijit/form/Button">Ellipse</button>
    </div>
    <div id="map" data-dojo-type="dijit/layout/ContentPane" data-dojo-props="region:'center'"></div>
  </div>

  </body>
</html>

I am very new to ArcGIS, therefore my question might be simple. I wonder if it's possible to substitute the background map by some other image, for example, the layer that represents a floor in a building? I have this image available in JPEG format and it has global coordinates assigned to it. So, how can I substitute a map by this image? Should I update these lines of code?

    map = new Map("map", {
      basemap: "streets",
      center: [-15.469, 36.428],
      zoom: 3
    });

Solution

Well, those background images are known as basemap in Gis term. ARCGIS js api provides multiple basemaps like topo, street, imagery etc.

To change the background/basemap you need to change the basemap keyword.

Example-

Change "streets" to "topo". It will change the basemap/background.

Note- you can try various types of basemaps which is available on arcgis api.

EDITED[30/May/2017]-

Here I am proposing you to use existing basemap provided by ESRI, However if you want to show your own images as backgroud/basemap then you need to publish/republish a basemap.

Hoping this will help you.