FixedBuggyClass.js

//////// FIXED
// See BuggyClass.js for explanations of problems with doing 
// default value assignment with || operator.
// gist: 274158   http://gist.github.com/gists/274158

/** A slightly better way to set default value, so `new FixedBuggyClass()` works as expected */
function FixedBuggyClass(param1, param2,param3) {
   if (param2 == null) param1 = "defaultValue";
   this.param1 = param1;
   if (param2 == null) param2 = true;
   this.param2 = param2;
   if (param3 == null) param3 = -1;
   this.param3 = param3;
 
   this.input = param1 + ".." + param2;  // lose original input, but matches this.derived now.
   this.derived = this.param1 + ".." + this.param2; 
   this.same = this.derived == this.input; // should always be true, right?
 
}
FixedBuggyClass.prototype.unexpected = function() {
   var res = [];
   for (attr in this) { 
       var t = typeof(this[attr]);
       if (t != "function" && t != "undefined") res.push(attr + "=" + this[attr]);
   }
   return res.join("\n")
}
FixedBuggyClass.prototype.toString = FixedBuggyClass.prototype.unexpected;
 
var show = self.consle ? console.log : function(msg) { alert(msg); }
 
var bugsMeDefault = new FixedBuggyClass(null, null)
 
// This is buggy:
var bugsMeNot = new FixedBuggyClass("ok", false,0);
 
 
///// May not get what you expect!!!
 
var results = [
bugsMeDefault,
bugsMeNot.unexpected(),
bugsMeNot.param1, 
bugsMeNot.param2 == false,
bugsMeNot.param3 == 0,
].join("\n\n");
 
show(results);