Can't retrieve result from AJAX objects with plain JavaScript -

trying implement own ajax prototype , not using jquery or other one. can't retrieve result, breakpoint, set on line doesn't fire:

the problem next part:

why undefined, if have init httpxml instance init() function:

i'm trying send request other part of program doing next:

var ajaxinstance = new gc3d.ajax(); ajaxinstance.init(); var response = ajaxinstance.sendrequest({     httpmethod: 'get',     urlendpoint: '/someservice?function=somefunctionname' }); 

full source of prototype:

gc3d.ajax = function() {     this.httprequest = undefined;     this.listexceptions = undefined; }; gc3d.ajax.prototype.init = function() {     this.listexceptions = [];      if ( window.xmlhttprequest ) this.httprequest = new xmlhttprequest();     else if ( window.activexobject ) {         try {             this.httprequest = new activexobject( 'microsoft.xmlhttp' );         }         catch ( exception ) {             this.listexceptions.push( exception );              try {                 this.httprequest = new activexobject( 'msxml2.xmlhttp' );             }              catch ( exception ) {                 this.listexceptions.push( exception );                  try {                     this.httprequest = new activexobject( 'microsoft.xmlhttp' );                 }                  catch ( exception ) {                     this.listexceptions.push( exception );                 }             }         }     }      if ( !this.httprequest ) {         console.error( 'can\'t create http request instance ajax! possible problems:' );         console.error( this.listexceptions );     }     else this.httprequest.onreadystatechange = this.getcontentfromrequest; }; gc3d.ajax.prototype.sendrequest = function( properties ) {     if ( this.httprequest !== undefined ) {         this.httprequest.open( properties.httpmethod, properties.urlendpoint );         this.httprequest.send();     }     else throw 'http request instance isn\'t defined!'; }; gc3d.ajax.prototype.getcontentfromrequest = function() {     if ( this.httprequest !== undefined ) {         if ( this.httprequest.readystate === 4) {             if ( this.httprequest.status === 200 ) return this.httprequest.responsetext;             else console.log( 'there problem request in gc3d.ajax.' );         }     } }; gc3d.ajax.prototype.get = function() {     return this.httprequest; }; 

what's incorrect , why isn't firing @ line above?

thanks

the problem this context losing here:

else this.httprequest.onreadystatechange = this.getcontentfromrequest; 

when i've applied event function above has lost instance.

let's imagine, don't know exact function name , anonymous function:

this.someevent.onsomething = function( item ) { ... }; 

and here it's losing in anonymous function because of scopes definition {}, closing visible space this.

so similar issue here code, when i've changed part to:

gc3d.ajax.prototype.getcontentfromrequest = function() {     if ( this.readystate === 4 ) {         if ( this.status === 200 ) return this.responsetext;         else console.log( 'there problem request in gc3d.ajax.' );     } }; 

and code working!