Arcgis api for javascript学习笔记(3.2X版本)-Map图层叠加以及基本操作

1. 不设置默认底图，第一个图层作为底图，然后叠加另外一个图层

先添加图层1，第一个图层1作为默认底图，然后在图层1上叠加图层2，并设置图层2的透明度为50%。

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4     <title>simple demo</title>
 5     <link rel="stylesheet" href="http://localhost:8003/arcgis_js_v320_api/library/3.20/3.20/esri/css/esri.css">
 6     <style type="text/css">
 7         html, body { margin: 0; padding: 0; height: 100%; width: 100%; }
 8         #viewDiv { width: 100%; height: 100%; }
 9     </style>
10 </head>
11 <body>
12     <div id="viewDiv"></div>
13     <script src="http://localhost:8003/arcgis_js_v320_api/library/3.20/3.20/init.js"></script>
14     <script type="text/javascript">
15         require([
16             "esri/map",
17             "esri/layers/ArcGISTiledMapServiceLayer",
18             "dojo/domReady!"],
19             function (Map, ArcGISTiledMapServiceLayer) {
20                 var map = new Map("viewDiv");
21                 var tms1 = new ArcGISTiledMapServiceLayer("http://cache1.arcgisonline.cn/arcgis/rest/services/ChinaOnlineCommunity/MapServer"); //图层1
22                 map.addLayer(tms1);
23                 var tms2 = new ArcGISTiledMapServiceLayer("http://services.arcgisonline.com/arcgis/rest/services/Demographics/USA_Projected_Population_Change/MapServer", { "opacity": 0.5 }); //图层2，透明度50%
24                 map.addLayer(tms2);
25             }
26         );
27     </script>
28 </body>
29 </html>

效果如下：