原以为span不同于input，事件冒泡会被父级标签吞噬，写了个测试事件冒泡的Demo，发现并不是想得那样。另外：event.stopPropagation()以及event.stopImmediatePropagation()并不能阻止span冒泡到a标签中，而简单粗暴的return false却可以。
1 <!DOCTYPE html> 2 <html> 3 <head> 4 <title>Bubbling</title> 5 <style type="text/css"> 6 * { 7 font-size:30px; 8 } 9 div { 10 border: 1px blue solid; 11 } 12 span { 13 border: 1px blue solid; 14 } 15 </style> 16 <script type="text/javascript"> 17 function setforeColor(sender) { 18 sender.style.color = "red"; 19 } 20 21 function setbgColor(sender) { 22 sender.style.background = "green"; 23 return false; 24 } 25 </script> 26 </head> 27 <body> 28 <div> 29 <span onclick="setforeColor(this)">span tag</span> in div 30 </div> 31 <br> 32 <div> 33 <input type="button" value="Button" onclick="setforeColor(this)"/> in div 34 </div> 35 <br> 36 <a href="https://www.baidu.com" style="text-decoration:none;display:block;"> 37 <span onclick="setforeColor(this);return false">span tag</span> in anchor 38 </a> 39 <br> 40 <a href="https://www.baidu.com" style="text-decoration:none;display:block;"> 41 <span onclick="setbgColor(this)">span tag</span> in anchor 42 </a> 43 </body> 44 </html>
更多参考：https://en.wikipedia.org/wiki/Event_bubbling、http://javascript.info/bubbling-and-capturing