<html><head><script>function copyText(){ document.getElementById("field2").value=document.getElementById("field1").value;}</script></head><body>字段1: <input type="text" id="field1" value="Hello World!"><br>字段2: <input type="text" id="field2"><br><br><button ondblclick="copyText()">复制文本</button><p>在按钮双击时触发函数。函数将字段1的文字信息复制到字段2。</p></body></html>