CaseInsensitiveLookup.js

function CaseInsensitiveLookup() {
  this.obj = {};
  this.keys = {};
  
  this.getKey = function(key) {
    if (key) {
      var lKey = key.toLowerCase(),
          lastKey = this.keys[lKey];
                            
      return this.keys[lKey] = (lastKey || key);
    }
  }
  
  this.getKeys = function() {
    return Object.keys(this.obj);
  }
  
  this.getValue = function(key) {
    return this.obj[this.getKey(key)];
  }
  
  this.setValue = function(key, value) {
    this.obj[this.getKey(key)] = value;
  }
  
  this.getObject = function() {
    return this.obj;
  }
}