Why do I get an Uncaught TypeError with private JS ES5 class call?

Question

I am attempting to make a class in JavaScript (ES5). However, when I call one method from another, I get the following error message in console:

Uncaught TypeError: root.abLog is not a function

The offending article in question (stripped down to show only the relevant parts) is as follows:

var abClass = function(options) {

    var root = this;

    this.checkAttach = function(text){
        root.abLog('Checking attached');
        /* snip */
    };

    var abLog = function(data) {
        console.log('abClass PATH: "'+vars.path+'"');
        console.log('abClass: '+data);
    };

};

Both root.abLog('Checking attached'); and this.abLog('Checking attached'); result in similar errors.

What have I done wrong with what I understand is a private method?

Can you also include how you instinciate your `abClass` as well as how you call your `abLog` method? — M0nst3R, Sep 12 '19 at 12:49
abLog has nothing to do with `this` hence the error. variables defined inside of a block are not part of `this` — epascarello, Sep 12 '19 at 12:50
Possible duplicate of [How do JavaScript closures work?](https://stackoverflow.com/questions/111102/how-do-javascript-closures-work) — Jared Smith, Sep 12 '19 at 12:54
Disregard previous comment - it looks like we are looking at this from two ways - one way being that the call of the function is wrong (and doesn't match the definition) and the other being that the definition is wrong (and doesn't match the call). — Lewis, Sep 12 '19 at 12:59

score 3 · Accepted Answer · answered Sep 12 '19 at 12:51

Call it without root or this like -

var abClass = function(options){

   var root = this;

   this.checkAttach = function(text){
       abLog('Checking attached');
       /* snip */
   };

   var abLog = function(data) {
       console.log('abClass PATH: "'+vars.path+'"');
       console.log('abClass: '+data);
   };

};

abLog is a private function of your abClass and the scope of this (attached to root in your case) gets a copy of your public members of the class, i.e. members directly attached via this.XXX - In your case, it's only checkAttach attached to this (hence making it a public member)

Check this JS bin to play around and debug

Why do I get an Uncaught TypeError with private JS ES5 class call?

1 Answers1