Zindex Order

<!--
  示例：图层叠放顺序
  要点：setZIndex 控制渲染次序，底图固定 0，业务层从 1 起算
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>图层叠放顺序</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:10px;align-items:center;font-size:12px;color:#58606e}
  .bar button{padding:4px 10px;border:1px solid #cfd4dc;border-radius:4px;
              background:#fff;cursor:pointer;font-size:12px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="btnOrange">橙色置顶</button>
  <button id="btnBlue">蓝色置顶</button>
  <span id="info">—</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;

  function rect(coords, color) {
    var ring = coords.concat([coords[0]]).map(function (p) {
      return fromLonLat(p);
    });
    return new ol.layer.Vector({
      source: new ol.source.Vector({
        features: [new ol.Feature({ geometry: new ol.geom.Polygon([ring]) })]
      }),
      style: new ol.style.Style({
        fill: new ol.style.Fill({ color: color }),
        stroke: new ol.style.Stroke({ color: 'rgba(22, 24, 29, 0.55)', width: 2 })
      })
    });
  }

  var blue = rect([
    [116.372, 39.900], [116.412, 39.900], [116.412, 39.924], [116.372, 39.924]
  ], 'rgba(31, 95, 208, 0.5)');

  var orange = rect([
    [116.392, 39.908], [116.432, 39.908], [116.432, 39.932], [116.392, 39.932]
  ], 'rgba(194, 65, 12, 0.5)');

  blue.setZIndex(2);
  orange.setZIndex(1);

  var base = new ol.layer.Tile({ source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}) });
  base.setZIndex(0);

  new ol.Map({
    target: 'map',
    layers: [base, blue, orange],
    view: new ol.View({
      center: fromLonLat([116.402, 39.916]),
      zoom: 13
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  var info = document.getElementById('info');
  function report() {
    info.textContent = '蓝色 zIndex=' + blue.getZIndex() + '，橙色 zIndex=' + orange.getZIndex();
  }

  document.getElementById('btnOrange').addEventListener('click', function () {
    orange.setZIndex(3);
    blue.setZIndex(2);
    report();
  });

  document.getElementById('btnBlue').addEventListener('click', function () {
    blue.setZIndex(3);
    orange.setZIndex(2);
    report();
  });

  report();
})();
</script>
</body>
</html>