最简单的方法来检索跨浏览器的XmlHttpRequest

检索适用于所有浏览器的XmlHttpRequest对象的最简单和最安全的方法是什么？ 没有任何额外的库。 有没有经常使用的代码片段？

PS我知道网上有大量的例子，但这正是我所问的原因：有太多不同的例子，我只是想要简单的东西，并certificate是可行的。

jQuery和其他库不是一个选项。 为什么jQuery的内存泄漏太严重了？

Answer 1

虽然我build议使用完整的库来简化使用，但在现代浏览器中使AJAX请求相当简单：

var req = new XMLHttpRequest(); req.onreadystatechange = function(){ if(this.readyState == 4){ alert('Status code: ' + this.status); // The response content is in this.responseText } } req.open('GET', '/some-url', true); req.send(); 

以下片段是基于quirksmode.org片段的更高级片段，甚至支持非常旧的浏览器（比Internet Explorer 7早）：

 function sendRequest(url,callback,postData) { var req = createXMLHTTPObject(); if (!req) return; var method = (postData) ? "POST" : "GET"; req.open(method,url,true); // Setting the user agent is not allowed in most modern browsers It was // a requirement for some Internet Explorer versions a long time ago. // There is no need for this header if you use Internet Explorer 7 or // above (or any other browser) // req.setRequestHeader('User-Agent','XMLHTTP/1.0'); if (postData) req.setRequestHeader('Content-type','application/x-www-form-urlencoded'); req.onreadystatechange = function () { if (req.readyState != 4) return; if (req.status != 200 && req.status != 304) { // alert('HTTP error ' + req.status); return; } callback(req); } if (req.readyState == 4) return; req.send(postData); } var XMLHttpFactories = [ function () {return new XMLHttpRequest()}, function () {return new ActiveXObject("Msxml3.XMLHTTP")}, function () {return new ActiveXObject("Msxml2.XMLHTTP.6.0")}, function () {return new ActiveXObject("Msxml2.XMLHTTP.3.0")}, function () {return new ActiveXObject("Msxml2.XMLHTTP")}, function () {return new ActiveXObject("Microsoft.XMLHTTP")} ]; function createXMLHTTPObject() { var xmlhttp = false; for (var i=0;i<XMLHttpFactories.length;i++) { try { xmlhttp = XMLHttpFactories[i](); } catch (e) { continue; } break; } return xmlhttp; } 

Answer 2

按照要求， 简单且经过validation的工作 ：

 function Xhr(){ /* returns cross-browser XMLHttpRequest, or null if unable */ try { return new XMLHttpRequest(); }catch(e){} try { return new ActiveXObject("Msxml3.XMLHTTP"); }catch(e){} try { return new ActiveXObject("Msxml2.XMLHTTP.6.0"); }catch(e){} try { return new ActiveXObject("Msxml2.XMLHTTP.3.0"); }catch(e){} try { return new ActiveXObject("Msxml2.XMLHTTP"); }catch(e){} try { return new ActiveXObject("Microsoft.XMLHTTP"); }catch(e){} return null; } 

折叠成一行，我们得到：

 function Xhr(){ try{return new XMLHttpRequest();}catch(e){}try{return new ActiveXObject("Msxml3.XMLHTTP");}catch(e){}try{return new ActiveXObject("Msxml2.XMLHTTP.6.0");}catch(e){}try{return new ActiveXObject("Msxml2.XMLHTTP.3.0");}catch(e){}try{return new ActiveXObject("Msxml2.XMLHTTP");}catch(e){}try{return new ActiveXObject("Microsoft.XMLHTTP");}catch(e){}return null; } 

Answer 3

不是100％确定你的问题 – 但如果你要求函数返回一个跨浏览器的XMLHTTP实例 – 我们已经在我们的本地ajax库使用了多年 – 在任何浏览器中从来没有问题

 function getXMLHTTP() { var alerted; var xmlhttp; /*@cc_on @*/ /*@if (@_jscript_version >= 5) // JScript gives us Conditional compilation, we can cope with old IE versions. try { xmlhttp=new ActiveXObject("Msxml2.XMLHTTP") } catch (e) { try { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP") } catch (E) { alert("You must have Microsofts XML parsers available") } } @else alert("You must have JScript version 5 or above.") xmlhttp=false alerted=true @end @*/ if (!xmlhttp && !alerted) { // Non ECMAScript Ed. 3 will error here (IE<5 ok), nothing I can // realistically do about it, blame the w3c or ECMA for not // having a working versioning capability in <SCRIPT> or // ECMAScript. try { xmlhttp = new XMLHttpRequest(); } catch (e) { alert("You need a browser which supports an XMLHttpRequest Object") } } return xmlhttp } 

Answer 4

一个更简单的方法：

检测IE：

 function detectIE() { var ua = window.navigator.userAgent, msie = ua.indexOf('MSIE '), trident = ua.indexOf('Trident/'), edge = ua.indexOf('Edge/'); if (msie > 0) {return parseInt(ua.substring(msie + 5, ua.indexOf('.', msie)), 10);} if (trident > 0) {var rv = ua.indexOf('rv:');return parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10);} if (edge > 0) {return parseInt(ua.substring(edge + 5, ua.indexOf('.', edge)), 10);} return false; } 

区分XMLhttp和XDomain：

 var url = "https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20weather.forecast%20where%20woeid%20in%20(select%20woeid%20from%20geo.places(1)%20where%20text%3D%27pune%2Cmh%27)&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithke" if (window.XDomainRequest && detectIE()) { var xdr = new XDomainRequest(); xdr.open("GET", url, false); xdr.onload = function () { var res = JSON.parse(xdr.responseText); if (res == null || typeof (res) == 'undefined') { res = JSON.parse(data.firstChild.textContent); } publishData(res); }; xdr.send(); } else { var xmlhttp = new XMLHttpRequest(); xmlhttp.onreadystatechange = function() { if (xmlhttp.readyState == 4) { if (xmlhttp.status == 200 || xmlhttp.status == 304) { publishData(JSON.parse(xmlhttp.responseText)); } else { setTimeout(function(){ console.log("Request failed!") }, 0); } } } xmlhttp.open("GET", url, true); xmlhttp.send(); } function publishData(data){ console.log(data); //Response } 

完整的例子可以在这里find