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?

Answer 1

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