Handwriting a Jsonp

native JSONP specifically implemented

First on the code:

    //http://www.baidu.com?aa=11&callback=my_jsonp04349289664328899    varJSONP =function(url,param,callback) {//process URL address, find? , if not? This variable has a "?", is there? This variable receives a &        varQueryString = Url.indexof ("?") = =-1? "?": "&"; //processing parameter {xx:xx}         for(varKinchparam) {QueryString+ = k + "=" + Param[k] + ' & ';//? K=para[k]        }        //Handling callback function names        varRandom = Math.random (). toString (). Replace (".", ""); varCbval = "My_jsonp" +Random; varCB = "callback=" +Cbval; QueryString+=CB; varScript = document.createelement ("Script"); SCRIPT.SRC= URL +querystring; //attach the name of the callback function to the windowWindow[cbval] =function(param) {//This is where the callback is performed and the callback is used to process the argumentscallback (param); //Delete this script when you get it.document.body.removeChild (script);        };    Document.body.appendChild (script); } JSONP ("Https://www.baidu.com", {aa:11},        function() {console.log (param); }        );

Ideas:

1. Abstract the string to be processed first

2. After processing the URL, create a new script tag to attach to the page

3. Hang the handled callback function on the Window object

4. Erase the script after the callback.

steps:

Take a random address, like Baidu.

• http://www.baidu.com?aa=11&callback=my_jsonp04349289664328899

• The address (? and previous content) to be processed

• Parameters (? following)

• callback function

var function (Url,para,callback) {}
Address, parameter, callback

Start processing URL Address

• The domain name is our own transfer, so as long as the processing of the contents of the good

var queryString = Url.indexof ("?") = =-1? "?": "&"; // look at the URL there is no?, if there is a description as long as the parameters are good, no words querystring default is? // there are usually several parameters to the address, so the data format is an object, such as {aa:11}  for (var in para) {  + = k + ' = ' + para[k] + ' & ';   // ?aa=11&}

Handling Callback Functions

• The idea of imitating JQ, the function name is random, avoid and the page of a function duplicate

• Requires a random non-floating-point number

• Name of parameter

var random = Math.random (). toString (). Replace (".", ""); // random non-floating-point number var cbvalue = "JP" + random; // You cannot do a function name with the beginning of a number var cb = "callback=" + cbvalue; // callback = jp016548432158485queryString + = CB; // placed behind the processing URL string

Create a script

var script = document.createelement ("script"= querystring;document.body.appendchild (script);

Mount the callback function on the page and pass the parameter

function (para) {  callback (para);   // take out the parameters and delete them, ladder.   document.body.removeChild (script);}

Complete, try Calling

Jsonp ("www.jd.com", {num:10},function() {  console.log (para);})

Handwriting a Jsonp