本篇文章为大家展示了XMLHttpRequest中的ajax是怎样的，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。
调用
function(Url) {
var XML = new XMLHttpRequest();
XML.onreadystatechange = function() {
if (XML.readyState == 4)
{
if (XML.status == 200)
{
//XML.responseText
}
else
{
//XML.statusText
}
}
else
{
//数据加载中...
}
};
XML.open("GET",Url);
XML.send(null);
};定义XMLHttpRequest 适应不同的浏览器
// IE support
if (window.ActiveXObject && !window.XMLHttpRequest)
{
window.XMLHttpRequest = function()
{
var msxmls = new Array('Msxml2.XMLHTTP.5.0','Msxml2.XMLHTTP.4.0','Msxml2.XMLHTTP.3.0','Msxml2.XMLHTTP','Microsoft.XMLHTTP');
for (var i = 0; i < msxmls.length; i++)
{
try
{
return new ActiveXObject(msxmls[i]);
}
catch (e)
{
}
}
return null;
};
}// Opera support
if (window.opera && !window.XMLHttpRequest)
{
window.XMLHttpRequest = function()
{
this.readyState = 0; // 0=uninitialized,1=loading,2=loaded,3=interactive,4=complete
this.status = 0; // HTTP status codes
this.statusText = '';
this._headers = [];
this._aborted = false;
this._async = true;
this._defaultCharset = 'ISO-8859-1';
this._getCharset = function()
{
var charset = _defaultCharset;
var contentType = this.getResponseHeader('Content-type').toUpperCase();
val = contentType.indexOf('CHARSET=');
if (val != -1)
{
charset = contentType.substring(val);
}
val = charset.indexOf(';');
if (val != -1)
{
charset = charset.substring(0, val);
}
val = charset.indexOf(',');
if (val != -1)
{
charset = charset.substring(0, val);
}
return charset;
};
this.abort = function()
{
this._aborted = true;
};
this.getAllResponseHeaders = function()
{
return this.getAllResponseHeader('*');
};
this.getAllResponseHeader = function(header)
{
var ret = '';
for (var i = 0; i < this._headers.length; i++)
{
if (header == '*' || this._headers[i].h == header)
{
ret += this._headers[i].h + ': ' + this._headers[i].v + '\n';
}
}
return ret;
};
this.getResponseHeader = function(header)
{
var ret = getAllResponseHeader(header);
var i = ret.indexOf('\n');
if (i != -1)
{
ret = ret.substring(0, i);
}
return ret;
};
this.setRequestHeader = function(header, value)
{
this._headers[this._headers.length] = {h:header, v:value};
};
this.open = function(method, url, async, user, password)
{
this.method = method;
this.url = url;
this._async = true;
this._aborted = false;
this._headers = [];
if (arguments.length >= 3)
{
this._async = async;
}
if (arguments.length > 3)
{
opera.postError('XMLHttpRequest.open() - user/password not supported');
}
this.readyState = 1;
if (this.onreadystatechange)
{
this.onreadystatechange();
}
};
this.send = function(data)
{
if (!navigator.javaEnabled())
{
alert("XMLHttpRequest.send() - Java must be installed and enabled.");
return;
}
if (this._async)
{
setTimeout(this._sendasync, 0, this, data);
}
else
{
this._sendsync(data);
}
};
this._sendasync = function(req, data)
{
if (!req._aborted)
{
req._sendsync(data);
}
};
this._sendsync = function(data)
{
this.readyState = 2;
if (this.onreadystatechange)
{
this.onreadystatechange();
}
var url = new java.net.URL(new java.net.URL(window.location.href), this.url);
var conn = url.openConnection();
for (var i = 0; i < this._headers.length; i++)
{
conn.setRequestProperty(this._headers[i].h, this._headers[i].v);
}
this._headers = [];
if (this.method == 'POST')
{ // POST data
conn.setDoOutput(true);
var wr = new java.io.OutputStreamWriter(conn.getOutputStream(), this._getCharset());
wr.write(data);
wr.flush();
wr.close();
}
// read response headers
// NOTE: the getHeaderField() methods always return nulls for me :(
var gotContentEncoding = false;
var gotContentLength = false;
var gotContentType = false;
var gotDate = false;
var gotExpiration = false;
var gotLastModified = false;
for (var i = 0; ; i++)
{
var hdrName = conn.getHeaderFieldKey(i);
var hdrValue = conn.getHeaderField(i);
if (hdrName == null && hdrValue == null)
{
break;
}
if (hdrName != null)
{
this._headers[this._headers.length] = {h:hdrName, v:hdrValue};
switch (hdrName.toLowerCase())
{
case 'content-encoding': gotContentEncoding = true; break;
case 'content-length' : gotContentLength = true; break;
case 'content-type' : gotContentType = true; break;
case 'date' : gotDate = true; break;
case 'expires' : gotExpiration = true; break;
case 'last-modified' : gotLastModified = true; break;
}
}
} // try to fill in any missing header information
var val;
val = conn.getContentEncoding();
if (val != null && !gotContentEncoding) this._headers[this._headers.length] = {h:'Content-encoding', v:val};
val = conn.getContentLength();
if (val != -1 && !gotContentLength) this._headers[this._headers.length] = {h:'Content-length', v:val};
val = conn.getContentType();
if (val != null && !gotContentType) this._headers[this._headers.length] = {h:'Content-type', v:val};
val = conn.getDate();
if (val != 0 && !gotDate) this._headers[this._headers.length] = {h:'Date', v:(new Date(val)).toUTCString()};
val = conn.getExpiration();
if (val != 0 && !gotExpiration) this._headers[this._headers.length] = {h:'Expires', v:(new Date(val)).toUTCString()};
val = conn.getLastModified();
if (val != 0 && !gotLastModified) this._headers[this._headers.length] = {h:'Last-modified', v:(new Date(val)).toUTCString()};
// read response data
var reqdata = '';
var stream = conn.getInputStream();
if (stream)
{
var reader = new java.io.BufferedReader(new java.io.InputStreamReader(stream, this._getCharset()));
var line;
while ((line = reader.readLine()) != null)
{
if (this.readyState == 2)
{
this.readyState = 3;
if (this.onreadystatechange)
{
this.onreadystatechange();
}
}
reqdata += line + '\n';
}
reader.close();
this.status = 200;
this.statusText = 'OK';
this.responseText = reqdata;
this.readyState = 4;
if (this.onreadystatechange)
{
this.onreadystatechange();
}
if (this.onload)
{
this.onload();
}
}
else
{
// error
this.status = 404;
this.statusText = 'Not Found';
this.responseText = '';
this.readyState = 4;
if (this.onreadystatechange)
{
this.onreadystatechange();
}
if (this.onerror)
{
this.onerror();
}
}
};
};
}// ActiveXObject emulation
if (!window.ActiveXObject && window.XMLHttpRequest)
{
window.ActiveXObject = function(type)
{
switch (type.toLowerCase())
{
case 'microsoft.xmlhttp':
case 'msxml2.xmlhttp':
case 'msxml2.xmlhttp.3.0':
case 'msxml2.xmlhttp.4.0':
case 'msxml2.xmlhttp.5.0':
return new XMLHttpRequest();
}
return null;
};
}上述内容就是XMLHttpRequest中的ajax是怎样的，你们学到知识或技能了吗？如果还想学到更多技能或者丰富自己的知识储备，欢迎关注亿速云行业资讯频道。
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