How to access object property from inside class function [duplicate]

Answer 1

Try this:

function File(data){
    this.data = data;

    var self = this;

    this.update = function (callback){
        var set = function(ajaxData){
            self.data = ajaxData.PcbFile;
        }
        getPcbFile(data.id, function(ajaxData){
            set(ajaxData);
            callback();
        });
    };
}

The value of this within a function depends on how that function is called. E.g., when you use the "dot" notation, someObj.someMethod() then within someMethod() you'd have this set to someObj. You can explicitly set this to some other object using the .apply() or .call() methods. Otherwise if you call a function as with set(ajaxData) then this will be the global object (window).

By keeping a reference to this outside your function (I prefer the variable name self for this purpose) you can reference it inside your function.

Answer 2

 (function(){
   var accessible = {
     prop1: 'blabla',
     verify: function(){
       console.log( this.prop1);
       return this;
     },
     deepAccess: function(){
       return function(){
         accessible.prop1 = 'bloblo';
         return function(){
           console.log("Deep access ", accessible.prop1);
         }
       }
     },
     insideFunction: function(){
       //here you can use both 'this' or 'accessible' 
                  this.prop1 = 'bleble';
                  return this;
       },
       prop2: 3.1415
    };
   return accessible;
})().verify().insideFunction().verify().deepAccess()()();

/* console shows:
 blabla
 bleble
 Deep access bloblo
*/

Answer 3

I learned this the hard way, you have to be careful with this. It always refers to the this in the current scope, not it's containing object. Whenever you wrap something in function() { ... }, this becomes of a different scope. In your case, duplicate the object to a local variable and manipulate it's .data property.

function File(data){
    this.data = data;
    var file = this; //call the variable whatever you want
    this.update = function (callback){
        var set = function(ajaxData){
            file.data = ajaxData.PcbFile;
        }
        getPcbFile(data.id, function(ajaxData){
            set(ajaxData);
            callback();
        });
    };
}

Answer 4

Cache this so you can refer to it in the same context some place else:

function File(data){

  var self = this;

  self.data = data;

  self.update = function (callback){
    var set = function(ajaxData){
      self.data = ajaxData.PcbFile;
    }
    getPcbFile(data.id, function(ajaxData){
      set(ajaxData);
      callback();
    });
  };
}