Javascript class instance in other class functions (nodejs)

Question

I deal with nodejs and i cannot figure out, why i cannot call class instance from another class function. Here is my code. Please help.

var StationDAO = require('./StationDAO.js');
var StationSearchCriteria = require('./StationSearchCriteria.js');

function GasStationService(lat, long, zoom) {
this.latitude = lat;
this.longitude = long;
this.zoom = zoom;
this.zoomToKilometers = 0.009;

/* ......... */

this.minLat = function () {
    return this.latitude - this.zoomToKilometers;
};

this.minLong = function() {
    return this.longitude - this.zoomToKilometers;
};

this.maxLat = function() {
    return this.latitude + this.zoomToKilometers;
};

this.maxLong = function() {
    return this.longitude + this.zoomToKilometers;
};

this.criteria = new StationSearchCriteria(this.minLat(), this.minLong(),     this.maxLat(), this.maxLong());
this.conn = new StationDAO(criteria); // why this doesnt work

Is StationDAO module defined as a single function bound to module.exports? — ilmirons, Commented Mar 13, 2014 at 10:06
It is class accessing to Elastic search DB and it is module.exports — TomHonner, Commented Mar 13, 2014 at 11:13
Is there any async code in StationDAO? (maybe something is not yet initialized when you are invoking it). — ilmirons, Commented Mar 13, 2014 at 11:22

0x_Anakin · Accepted Answer · 2014-03-13 15:12:26Z

1

you are passing criteria which is not defined i assume you wanted to pass this.criteria isntead.

this.criteria = new StationSearchCriteria(this.minLat(), this.minLong(), this.maxLat(), this.maxLong());
this.conn = new StationDAO(this.criteria); //this should work

edited Mar 13, 2014 at 15:12

answered Mar 13, 2014 at 10:05

0x_Anakin

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if ` criteria ` is not defined then how this.criteria is existing ?
– Balayesu Chilakalapudi
Commented Mar 13, 2014 at 10:30
this.criteria is not the same as criteria. I seriously dont understand your comment.
– 0x_Anakin
Commented Mar 13, 2014 at 11:27
'this' pointer refers the current object's variable, in the problem statement 'criteria' is a variable which is the instance of StationSearchCriteria class and is already initialized.
– Balayesu Chilakalapudi
Commented Mar 13, 2014 at 11:48
1

+1'd this to bring it to zero since I think someone downvoted it not understanding it. Or maybe I am not understanding. I don't know why someone thinks that foo and this.foo would be the same thing.
– barry-johnson
Commented Mar 13, 2014 at 14:50

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