Button Title

<!--
  说明：控件按钮提示文本的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：querySelector 控件按钮 + title/aria-label + 自定义 tooltip
  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>控件按钮提示文本</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;flex-wrap:wrap;font-size:12px;color:#58606e}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  .bar button{font:inherit;padding:3px 9px;border:1px solid #c9ced6;background:#fff;
       border-radius:5px;cursor:pointer;color:#333}
  .bar button:hover{background:#eef2f8}
  .bar input[type=range]{width:110px;vertical-align:middle}
  .bar input[type=text]{font:inherit;padding:2px 6px;border:1px solid #c9ced6;border-radius:4px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .panel{flex:0 0 auto;max-height:34%;overflow:auto;padding:8px 12px;font-size:12px;
       background:#fff;border-top:1px solid #e3e6ea;color:#3d4451}
  .panel pre{margin:0;font-family:Consolas,"Courier New",monospace;font-size:11px;
       white-space:pre-wrap;word-break:break-all;line-height:1.5}
  .ol-attribution{font-size:11px}
  .ctrl-tip{position:fixed;z-index:9;padding:4px 8px;background:#2b3444;color:#fff;
    font-size:12px;border-radius:4px;pointer-events:none;box-shadow:0 2px 6px rgba(0,0,0,.2)}
</style>
</head>
<body>
<div class="bar">
<span>把鼠标移到右上角 + / − 按钮</span>
<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') {
    var errBox = document.getElementById('map');
    if (errBox) {
      errBox.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;
  var map = new ol.Map({
    target: 'map',
    layers: [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'})})],
    view: new ol.View({center: fromLonLat([116.397, 39.909]), zoom: 11}),
    controls: ol.control.defaults.defaults({attribution: false, zoom: true, rotate: false})
  });

  var info = document.getElementById('info');
  var tip = document.createElement('div');
  tip.className = 'ctrl-tip';
  tip.style.display = 'none';
  document.body.appendChild(tip);

  function show(text, x, y) {
    tip.textContent = text;
    tip.style.display = 'block';
    tip.style.left = (x + 12) + 'px';
    tip.style.top = (y - 30) + 'px';
  }

  function hide() {
    tip.style.display = 'none';
  }

  function bind(el, text) {
    el.addEventListener('mouseenter', function (evt) { show(text, evt.clientX, evt.clientY); });
    el.addEventListener('mousemove', function (evt) { show(text, evt.clientX, evt.clientY); });
    el.addEventListener('mouseleave', hide);
    el.addEventListener('focus', function () {
      var r = el.getBoundingClientRect();
      show(text, r.left, r.top);
    });
    el.addEventListener('blur', hide);
  }

  function decorate() {
    var zin = document.querySelector('.ol-zoom-in');
    var zout = document.querySelector('.ol-zoom-out');
    if (!zin || !zout) { return; }

    zin.setAttribute('title', '放大一级（快捷键 +）');
    zin.setAttribute('aria-label', '放大一级');
    zout.setAttribute('title', '缩小一级（快捷键 -）');
    zout.setAttribute('aria-label', '缩小一级');

    bind(zin, '放大一级，以视图中心为基准');
    bind(zout, '缩小一级，以视图中心为基准');

    info.textContent = 'title 与 aria-label 已改写 · 键盘 Tab 聚焦也会显示提示';
  }

  map.once('rendercomplete', decorate);
})();
</script>
</body>
</html>