Javascript prototypal inheritance base function undefined

Question

Trying to get to grips with OO prototypal vanilla javascript inheritance coming from c# background.

I have a base "class" that does a HTTP GET. I want to inherit from this so that sub classes can encapsulate variations of this HTTP GET.

In the following code I get a httpGet is undefined error in the getUser function. My end goal is to get a call to a nice simple method such as the userComms.getUser()

// declare base class
function HttpComms() { }
HttpComms.prototype.httpGet = function (url, callback) {
  // Code to do http get request
};

// declare sub class
function UserComms() {
    this.getUser = function () {
        // error thrown here:
        httpGet('user/get', function (data) {
            console.log(data);
        });
    }
}
// hookup prototypal relationship between base and sub
UserComms.prototype = Object.create(HttpComms.prototype);

// create and call sub class.
var userComms = new UserComms();
userComms.getUser();

Why do I get the error and what would be the most flexible way to get this working?

Igor · Accepted Answer · 2015-10-09 15:21:40Z

3

Note this. in front of httpGet:

function UserComms() {
    this.getUser = function () {
        // error thrown here:
        this.httpGet('user/get', function (data) {
            console.log(data);
        });
    }
}

answered Oct 9, 2015 at 15:21

Igor

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