getters and setters

gistfile1.js

  function makeSmart(obj) {
    obj.__bound__ = {};
  }
 
  function isSmart(obj) {
    return '__bound__' in obj;
  }
 
  function makeSmartProperty(obj, property) {
    var oldVal = obj[property];
 
    obj.__bound__[property] = [];
 
    var bound = obj.__bound__;
 
    // Apply magic
    Object.defineProperty(obj, property, {
      set: function(v) {
        // set the stored value
        bound[property].__value__ = v;
        var fns = bound[property];
        // fire our handlers
        for (var i = 0; i < fns.length; i++) {
          // for each fn, call fn(v)
          fns[i](v);
        }
      },
      get: function() {
        return bound[property].__value__;
      }
    });
 
    // apply an old value if it existed
    if (typeof oldVal !== 'undefined') {
      obj[property] = oldVal;
    }
  }
 
  function isSmartProperty(obj, property) {
    return obj.__bound__ && (property in obj.__bound__);
  }
 

 // wire data to DOM.
function link(obj, property, fn) {

  // set up smartness
  if (!isSmart(obj)) {
    makeSmart(obj);
  }

  if (!isSmartProperty(obj, property)) {
    makeSmartProperty(obj, property);
  }

  // call our handler once to initialize things
  fn(obj[property]);

  obj.__bound__[property].push(fn);
}

var manifest = {};

function renderJSON() {
  //  var prettyManifest = _.omit(manifest, '__bound__');
  var prettyManifest = manifest;
  console.log(JSON.stringify(prettyManifest));
}

link(manifest, 'name', renderJSON);

manifest.name = 'My Name';