ASP.NET MVC - 在onSuccess函数中获取对'triggerElement'的引用？

Question

是否有可能获得对onSuccess函数中调用Ajax请求的triggerElement的引用？

<%=Ajax.ActionLink("x", a, r, New AjaxOptions With {.OnSuccess = _
         "function(context) {alert('get triggerElement reference here?');}" })%>

Answer 1

该页面呈现为:
<a href="/<whatever>/<action>"onclick =" Sys.Mvc.AsyncHyperlink.handleClick(this,new Sys.UI.DomEvent(event),{insertionMode:Sys.Mvc. InsertionMode.replace,onSuccess:Function.createDelegate(this,function(context){alert('get triggerElement reference here？');})});"> x </a>

所以我们来看看Sys.Mvc.AsyncHyperlink.handleClick里面Scripts\MicrosoftMvcAjax.debug.js:

Sys.Mvc.AsyncHyperlink.handleClick = function Sys_Mvc_AsyncHyperlink$handleClick(anchor, evt, ajaxOptions) {
    /// omitted doc comments
    evt.preventDefault();
    Sys.Mvc.MvcHelpers._asyncRequest(anchor.href, 'post', '', anchor, ajaxOptions);
}

因此ActionLink的呈现到锚定("a")的标签,与"点击"事件,它使用Sys.Mvc.AsyncHyperlink.handleClick与此作为参数之一,映射到锚定.
然后是锚点作为第四个参数的这个Sys.Mvc.MvcHelpers._asyncRequest调用.我们来看看:Sys.Mvc.MvcHelpers._asyncRequest

Sys.Mvc.MvcHelpers._asyncRequest = function Sys_Mvc_MvcHelpers$_asyncRequest(url, verb, body, triggerElement, ajaxOptions) {
    /// omitted documentation
    if (ajaxOptions.confirm) {
        if (!confirm(ajaxOptions.confirm)) {
            return;
        }
    }
    if (ajaxOptions.url) {
        url = ajaxOptions.url;
    }
    if (ajaxOptions.httpMethod) {
        verb = ajaxOptions.httpMethod;
    }
    if (body.length > 0 && !body.endsWith('&')) {
        body += '&';
    }
    body += 'X-Requested-With=XMLHttpRequest';
    var requestBody = '';
    if (verb.toUpperCase() === 'GET' || verb.toUpperCase() === 'DELETE') {
        if (url.indexOf('?') > -1) {
            if (!url.endsWith('&')) {
                url += '&';
            }
            url += body;
        }
        else {
            url += '?';
            url += body;
        }
    }
    else {
        requestBody = body;
    }
    var request = new Sys.Net.WebRequest();
    request.set_url(url);
    request.set_httpVerb(verb);
    request.set_body(requestBody);
    if (verb.toUpperCase() === 'PUT') {
        request.get_headers()['Content-Type'] = 'application/x-www-form-urlencoded;';
    }
    request.get_headers()['X-Requested-With'] = 'XMLHttpRequest';
    var updateElement = null;
    if (ajaxOptions.updateTargetId) {
        updateElement = $get(ajaxOptions.updateTargetId);
    }
    var loadingElement = null;
    if (ajaxOptions.loadingElementId) {
        loadingElement = $get(ajaxOptions.loadingElementId);
    }
    var ajaxContext = new Sys.Mvc.AjaxContext(request, updateElement, loadingElement, ajaxOptions.insertionMode);
    var continueRequest = true;
    if (ajaxOptions.onBegin) {
        continueRequest = ajaxOptions.onBegin(ajaxContext) !== false;
    }
    if (loadingElement) {
        Sys.UI.DomElement.setVisible(ajaxContext.get_loadingElement(), true);
    }
    if (continueRequest) {
        request.add_completed(Function.createDelegate(null, function(executor) {
            Sys.Mvc.MvcHelpers._onComplete(request, ajaxOptions, ajaxContext);
        }));
        request.invoke();
    }
}

所以原始锚点现在是triggerElement,但正如你所看到的,这个参数从未在函数体中使用过.
所以,如果你想对triggerElement有某种"正式"(或记录)的引用 - 没有这样的事情.
但是,嘿,这是JavaScript,所以只要浏览器没有移动到另一个页面,包括调用堆栈,你几乎可以访问任何东西.例如:

<script type="text/javascript">
function a(p, q)
{
    b();
}

function b() {
    var x = arguments.caller[1];
    alert(x); // boo!
}

a(789, "boo!");

</script>

所以最终你可以破解它并访问原始锚点.我建议你做以下事情:

• 编写一个要在中调用的函数 OnBegin.
• 在此函数内部,访问原始文件triggerElement,并将其作为属性添加到原始文件中 ajaxOptions(也可以访问)
• 然后,在该OnSuccess函数中,访问您的黑客属性 ajaxOptions.