JS face Question-----communication Class

Topic 1: What are homologous policies and limitations

Topic 2: How to communicate back and forth

Ajax WebSocket CORS

Topic 3: How to create Ajax

Workflow for XMLHttpRequest objects

Compatibility processing

Trigger conditions for events

The order in which events are triggered

Util.json =function(options) {varopt ={url:‘‘, Type:' Get ', Data: {}, success:function() {}, error:function () {},     };     Util.extend (opt, options); if(opt.url) {varXHR =XMLHttpRequest?NewXMLHttpRequest ():NewActiveXObject (' microsoft.xmlhttp '); vardata =opt.data, URL=opt.url, Type=opt.type.toUpperCase (), Dataarr= [];  for(varKinchData) {dataarr.push (k+ ' = ' +data[k]); }         if(type = = = ' GET ') {url= URL + '? ' + dataarr.join (' & ')); Xhr.open (type, Url.replace (/\?$/g, "),true);         Xhr.send (); }         if(type = = = ' POST ') {xhr.open (type, url,true); Xmlhttp.setrequestheader (' Content-type ', ' application/x-www-form-urlencoded '); Xhr.send (dataarr.join (' & ')); } xhr.onload=function () {             if(xhr.status = = = | | xhr.status = = 304) {                 varres; if(opt.success && opt.successinstanceofFunction) {res=xhr.responsetext; if(typeofres = = = ' String ') {res=Json.parse (res);                     Opt.success.call (xhr, res); }                 }             } Else {                 if(opt.error && Opt.errorinstanceofFunction)                 {opt.error.call (xhr, res);     }             }         }; } };

Topic 4: Several ways to communicate across domains

JSONP Hash PostMessage WebSocket CORS

JSONP (most commonly used, not explained Here)

Hash　

// using hash, The scene is the current page A through the IFRAME or frame embedded Cross-domain page B      // the pseudo code in a is as Follows:      var B = document.getElementsByTagName (' iframe ');       = B.src + ' # ' + ' data ';       // the Pseudo-code in B is as follows      function () {          var data = window.location.hash;      };

PostMessage

// postMessage      // window A (http:a.com) sends information to a cross-domain window B (http:b.com)      Bwindow.postmessage (' Data ', ' http://B.com ');       // Listening in window b      function (event) {          console.log (event.origin); // http:a.com          Console.log (event.source); // Awindow          Console.log (event.data); // Data      false);

　　WebSocket

//Websocket "references" http://www.ruanyifeng.com/blog/2017/05/websocket.html      varWS =NewWebSocket (' wss://echo.websocket.org '); Ws.onopen=function(evt) {console.log (' Connection open ... '); Ws.send (' Hello websockets! ');      }; Ws.onmessage=function(evt) {console.log (' Received Message: ', evt.data);      Ws.close ();      }; Ws.onclose=function(evt) {console.log (' Connection Closed. '); };

　　CORS

// CORS "reference" http://www.ruanyifeng.com/blog/2016/04/cors.html      // URL (required), options (optional)      Fetch ('/some/url/', {          ' get ',      }). then (function  (response) {      }). Catch (function  (err) {        //  error, equivalent to then second argument, but this is better to be more intuitive      });

JS face Question-----communication Class