javascript - Q promises - How does scope work? -

How does the radius of Q work? As far as I know that "then" callback is called from window, like setTimeout.

In this example (an example to understand how it works):

  var getFileText = function {var deferred = Q.defer (); Server.readFile ("foo.txt", "utf-8", function (error, text) {if (error) {deferred.reject (new error (error)); else {deferred.resolve (text);}} ); Refund refund. }; Var fu = function () {getFileText () Then (this.showFile); }; Foo.prototype.showFile = function (text) {this.text = text; Console.log (text); }; Var foo = new Foo ();   
 I am using binds to keep text in foo example:  
  var foo = function () {getFileText (). Then (this .showFile.bind (this)); };   
 Is there any other way?   
 
 
 
 How does the scope of Q work?   
 You are looking for  context .  
 
 I know the callback "then" is called from the window   
 Well, on  on  global context, yes. It has to be called from  undefined  to  thisArg .  
 
 I am using the bind. Is there any other way?   
 In the context of the example only a long with the variable,  
  var that = it; GetFileText () Then (work (text) {that.text = text; // or longer: // that.showFile (text);});