Arc gis api for js比例尺，书签

  dojo.require("esri.map");
        dojo.require("esri.dijit.Scalebar");
        dojo.require("esri.dijit.Bookmarks");
        dojo.require("esri.dijit.BookmarkItem");

  var scalebar = new esri.dijit.Scalebar({
                map: myMap,
                // "dual" displays both miles and kilmometers
                // "english" is the default, which displays miles
                // use "metric" for kilometers
                scalebarUnit: "dual"
            }, dojo.byId("scalebardiv"));

              Books = new esri.dijit.Bookmarks({
                map: myMap,
                editable: "true"
            }, dojo.byId("bookmarks"));

            dojo.connect(button1, "click", addBook);

        }
        function addBook() {

            var bookextent = myMap.extent;

            var bookmarkItem = new esri.dijit.BookmarkItem({
                "extent": bookextent,
                "name": "北京"
            });
            Books.addBookmark(bookmarkItem);
        }