XMLHttpRequest Post 上的 send() 数据参数的最大长度

2022-01-15 00:00:00 xmlhttprequest javascript ajax

对于主要浏览器实现，您可以在 XMLHttpRequest 的 send 方法中使用的字符串数据长度是否有文档记录?

Is there a documented max to the length of the string data you can use in the send method of an XMLHttpRequest for the major browser implementations?

当数据超过大约 3k 时，我遇到了 JavaScript XMLHttpRequest Post 在 FireFox 3 中失败的问题.我假设 Post 的行为与传统的 Form Post 相同.

I am running into an issue with a JavaScript XMLHttpRequest Post failing in FireFox 3 when the data is over approx 3k. I was assuming the Post would behave the same as a conventional Form Post.

W3C 文档提到 send 方法的数据参数是 DOMString，但我不确定主流浏览器是如何实现的.

The W3C docs mention the data param of the send method is a DOMString but I am not sure how the major browsers implement that.

这是我的 JavaScript 的简化版本，如果 bigText 超过 3k 则失败，否则它可以工作...

Here is a simplified version of my JavaScript, if bigText is over about 3k it fails, otherwise it works...

var xhReq = createXMLHttpRequest();

function createXMLHttpRequest() {
  try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
  try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {}
  try { return new XMLHttpRequest(); } catch(e) {}
  alert("XMLHttpRequest not supported");
  return null;
}

function mySubmit(id, bigText) {
  var url    = "SubmitPost.cfm";
  var params = "id=" + id + "&bigtext=" + encodeURI(bigText);

  xhReq.open("POST", url, true);

  //Send the header information along with the request
  xhReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  xhReq.setRequestHeader("Content-length", params.length);
  xhReq.setRequestHeader("Connection", "close");

  xhReq.onreadystatechange = onPostSubmit;
  xhReq.send(params);
}

function onPostSubmit() {

  if (xhReq.readyState==4 || xhReq.readyState=="complete")
     { 
     if (xhReq.status != 200)
        {
        alert('BadStatus');
        return;
        }
    } 
}

推荐答案

我相信最大长度不仅取决于浏览器，还取决于网络服务器.例如，Apache HTTP 服务器有一个 LimitRequestBody 指令，它允许从 0 字节到 2GB 的数据.

I believe the maximum length depends not only on the browser, but also on the web server. For example, the Apache HTTP server has a LimitRequestBody directive which allows anywhere from 0 bytes to 2GB worth of data.

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