javascript – FireFox扩展：如何通过jQuery访问页面元素？

我使用以下代码：

   var myExtension = {
    init: function() {
        // The event can be DOMContentLoaded, pageshow, pagehide, load or unload.
        if(gbrowser) gbrowser.addEventListener("DOMContentLoaded", this.onPageLoad, false);
    },
    onPageLoad: function(aEvent) {
        var doc = aEvent.originalTarget; // doc is document that triggered the event
        var win = doc.defaultview; // win is the window for the doc
        //alert("page is loaded \n" +doc.location.href);
       // alert(doc.location.href.indexOf("facebook.com"));
        if(doc.location.href.indexOf("facebook.com") == -1) 
        {
            return;
        }
        alert("we are here");
        alert($("#blueBar").html());
    }
}
window.addEventListener("load", function load(event){
    window.removeEventListener("load", load, false); //remove listener, no longer needed
    myExtension.init();  
},false);

它不断给出未定义的错误

解决方法:

$()默认使用当前窗口的文档.在你的情况下,这实际上是browser.xul.你需要对你已经通过var doc = aEvent.originalTarget;获得的子文档进行操作,所以这应该工作我认为(未经测试)

$(doc).find("#blueBar")