The native javascript implementation parses XML documents and strings

Written before 1 article "use the method of analytical XML jquery" link is https: / / www ofstack. com article / 54842. htm, article explained in detail the jQuery and string conversion method, focuses on javascript xml operation here.

The general code is as follows:

var XMLHttp = null;
if (window.XMLHttpRequest) { // Modern Browser 
  XMLHttp = new XMLHttpRequest();
} else if (window.ActiveXObject) {
  XMLHttp = new ActiveXObject("Microsoft.XMLHTTP"); //IE5/IE6
}
if (XMLHttp !== null) {
  XMLHttp.onreadystatechange = function() {
    if (XMLHttp.readyState === 4) {
      if (XMLHttp.status === 200 || XMLHttp.status === 304) {
        // var XMLDom = XMLHttp.responseXML; // parsing XML The document 
        var XMLDoc = XMLHttp.responseText; // parsing XML string 
        var XMLDom = (new DOMParser()).parseFromString(XMLDoc, "text/xml");
        // I'm going to write the asynchronous code here 
        console.log(XMLDom);
        console.log("world"); // After the world
      }
    }
  };
  XMLHttp.open("get", "test1.xml", true);
  XMLHttp.send();
  // The non-asynchronous code is written here 
  console.log("hello"); // Came first hello
}

Step 1: Create XMLHTTPREQUEST:

var XMLHttp = null;
if (window.XMLHttpRequest) { // Modern Browser 
  XMLHttp = new XMLHttpRequest();
} else if (window.ActiveXObject) {
  XMLHttp = new ActiveXObject("Microsoft.XMLHTTP"); //IE5/IE6
}

Step 2: Check ONREADYSTATECHANGE (non-asynchronous, not required) :

if (XMLHttp !== null) {
  XMLHttp.onreadystatechange = function() {
    if (XMLHttp.readyState === 4) {
      if (XMLHttp.status === 200 || XMLHttp.status === 304) {
        // I'm going to write the asynchronous code here 
      }
    }
  };
  XMLHttp.open("get", "test1.xml", true);
  XMLHttp.send();
  // The non-asynchronous code is written here 
}

Step 3: Parse XML documents or strings (asynchronous) :

XMLHttp.onreadystatechange = function() {
    if (XMLHttp.readyState === 4) {
      if (XMLHttp.status === 200 || XMLHttp.status === 304) {
        // var XMLDom = XMLHttp.responseXML; // parsing XML The document 
        var XMLDoc = XMLHttp.responseText; // parsing XML string 
        var XMLDom = (new DOMParser()).parseFromString(XMLDoc, "text/xml");
        // I'm going to write the asynchronous code here 
        console.log(XMLDom);
      }
    }
  };
  

Step 4: Parse XML documents or strings (non-asynchronous) :

if (XMLHttp !== null) {
  // XMLHttp.onreadystatechange = function() {
  //   if (XMLHttp.readyState === 4) {
  //     if (XMLHttp.status === 200 || XMLHttp.status === 304) {}
  //   }
  // };
  XMLHttp.open("get", "test1.xml", false);
  XMLHttp.send();
  // The non-asynchronous code is written here 
  // var XMLDom = XMLHttp.responseXML; // parsing XML The document 
  var XMLDoc = XMLHttp.responseText; // parsing XML string 
  var XMLDom = (new DOMParser()).parseFromString(XMLDoc, "text/xml");
  // I'm going to write the asynchronous code here 
  console.log(XMLDom);
}