The jQuery load() method is a simple and powerful ajax method.
load() retrieves data from the server and places the returned data in the selected element.grammar
$(selected).load(URL,data,callback);
Where:
URL s are required, and consecutive are optional. The callback parameter is the function that the load() method is required to execute after execution.
For example:
//This is what loads the test text read from the txt file into the DIV with id div1
$("#div1").load("txt/test.txt")；
With callback function:
$("#btn").click(function(){
$("#div1").load("txt/text.txt",function(responseTxt,statusTxt,xhr){
if(statusTxt=="success"){
alert("Loading succeeded");
alert(responseTxt);
}
if(statusTxt=="error"){
alert("error:"+xhr.status+":"+xhr.statusTxt);
}
});});
In the code above:
1. responseTxt: Contains results when the call succeeds
2. statusTxt: Contains call status
3. xhr: Contains the XMLHttpRequest object.
Practical application
: 
sy.showUrlTab=function(id,title,url,pid){
/**
* 1:Left menu click jump function
*/
url = "/projectName-html"+url;
$("#mainContent").load(url,function(result){
/**
* Dynamic loading of js files
* Solution load js cannot debug
* Note that the naming rule html has the same name as the js file name
*/
var script = document.createElement("script");
script.type = "text/javascript";
if(typeof(callback) != "undefined"){
if (script.readyState) {
script.onreadystatechange = function () {
if (script.readyState == "loaded" || script.readyState == "complete") {
script.onreadystatechange = null;
callback();
}
};
} else {
script.onload = function () {
callback();
};
}
}
script.src = url.replace('.html','.js')+"?version="+sy.version;
document.body.appendChild(script);
});
// $.getScript("admin/qrcode/qrcodeList.js?version=20171213");
/*document.write('<script src="admin/operators/operatorsInfo.js?version=20171213"></script>');*/
ps: url: mainContext Page url Full Path
id: mainContext Of id
pid:mainContext Superior menu Of id