首頁 > 開發者 > JavaScript
[1]描述了firefox，safari 有一個bug和DOM 3 規範不一致：在event.currentTarget等於event.target的時候（即event flow處於target phase時），會調用添加到currentTarget上的useCapture為true的listener。 我最近調netsurf也遇到一個相關的bug ： alert() 被調了兩次。html 代碼：
<html> <head> <title>alert onclick example</title> <script type="text/javascript"> function causealert() { var txt = document.getElementById("p1").textContent; alert(txt); } </script> </head> <body> <div style="border: 1px solid red"> <p id="p1">First line of paragraph.<br /></p> </div><br /> <button id="button1" >add another textNode.</button> <script> var Button1 = document.getElementById("button1"); /*var Button1Click = function() { alert(1); }; Button1.addEventListener("click", Button1Click, false);*/ Button1.onclick = causealert; </script> </body> </html>
通過gdb， 定位到是_dom_node_dispatch_event()裡面的問題： /* The capture phase */ for (targetnr = ntargets; targetnr > 0; --targetnr)... /* Bubbling phase */ evt->phase = DOM_BUBBLING_PHASE; for (targetnr = 0; targetnr < ntargets; ++targetnr) 事件流是這樣的： p1(root)-->p2-->... --> pm --> T (capturing phase), T (target phase), T--> pm --> ... --> p1 (bubbling phase). 規範規定capturing 和bubbling 只能選其一， 代碼中在 js_dom_event_add_listener()是選capturing。因此就解釋了為什麼alert 被執行兩回了。 修改： 根據DOM 3 規範，把上面的0改成1就行了。 Ref
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
