ajax triggers,AJAX triggers ReadyState 4 several times in IE-优快云博客

在 IE8 浏览器中，用户遇到一个特定问题：某些 AJAX 请求的 readyState 会触发多次，导致行为不一致。问题只出现在少数特定链接上，而其他 AJAX 链接则正常工作。问题发生时，用户已在 AJAX UI 中进行过导航，点击了多个 AJAX 链接，但每个请求都使用同一个全局变量 xmlHttp。怀疑可能是 IE8 在每次调用 ajaxPost 函数时没有正确替换 onreadystatechange 处理器导致的。其他浏览器如 Safari、Firefox 和 Chrome 没有此问题。解决方案可能涉及清理或适配 IE8 的行为。

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I am experiencing a strange problem where IE8 will fire readyState 4 three or four times on an ajax request. This happens often but not always, and only for a couple of specific links - the rest of my ajax links are fine. My object creation and onreadystatechange handler are basic, ie.

function ajaxPost(params) {

try {

// Firefox, Opera 8.0+, Safari

xmlHttp = new XMLHttpRequest();

} catch (e) {

// Internet Explorer

try {

xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {

try {

xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

} catch (e) {

alert('Unsupported Browser');

}

xmlHttp.onreadystatechange = function() {

if (xmlHttp.readyState == 4) {

// Do something

}

xmlHttp.open("POST", path_to_script);

xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");

xmlHttp.setRequestHeader("Cache-Control", "must-revalidate");

xmlHttp.send(params);

}

Not sure if this is relevant - but at the points where the problem happens the user has already been navigating an ajax UI. They have clicked several other ajax links without reloading the page - each link uses a new xmlHttpRequest object with the same global variable name (xmlHttp), but each ajax request finishes before another can be issued. Do I need to do any "cleanup" or something for IE8? This has never happened using Safari, Firefox, Chrome, or any other browser.

Any insight would be much appreciated.

Thanks, Brian

Since your xmlHttp object is global, may be IE8 assigns a new onreadystatechange each time you call ajaxPost instead of replacing it.

That may explain an erratic behavior, as it depends on the number of calls to ajaxPost.