Watch out for context part 1

context_pitfall_ex.js

// create Logger constructor with few properties
var Logger = function(id) {
    this.container = document.getElementById(id);
    this.counter = 0;
}

// add functionalities with prototype
Logger.prototype.log = function(msg) {
    this.container.innerHTML = msg ;
    this.counter++;
}

Logger.prototype.getCounter = function() {
    this.log(this.counter);
}

// create new logger object and log few messages
var logger = new Logger('logger');

logger.log('wow');
logger.log('plum');