pathObserver.js

// simple path observing

function O(original, parentsWatcher, path) {
  this.original = original;
  this.path = path;
  this.parentsWatcher = parentsWatcher;
  
  Object.observe(this.original, function(changes) {
    changes.forEach(function(change) {
      if((change.type === 'add' || change.type === 'update') && typeof this.original[change.name] === "object") {
        var child = new O(this.original[change.name], function(childPath, childNew, childOld) {
          this.parentsWatcher(change.name+'.'+childPath, childNew, childOld);
        }.bind(this), change.name);
      }
      this.parentsWatcher(change.name, this.original[change.name], change.oldValue);
    }.bind(this));
  }.bind(this));
}

var model = {};
var modelStream = new O(model, 'test', function(path, newValue, oldValue) {
  console.log(path, JSON.stringify(newValue), JSON.stringify(oldValue));
});

function objectForEach(obj, cb) {
  Object.keys(obj).forEach(function(key) {
    cb(obj[key], key, obj);
  });
}
function arrayForEach(arr, cb) {
  arr.forEach(cb);
}

// simpler path observing
function pathObserver(obj, cb) {
  function iterator(obj, cb, path) {
    var type = Object;
    var forEach = objectForEach;
    if(Array.isArray(obj)) {
      type = Array;
      forEach = arrayForEach;
    }
    forEach(obj, function(val, key) {
      if(typeof val === "object") {
        iterator(val, cb, (path ? path+'.' : '')+key);
      }
    });
    type.observe(obj, function(changes) {
      while(changes.length) {
        var change = changes.shift();
        var cPath = (path ? path+'.' : '')+change.name;
        var cType = change.type;
        var cOld = change.oldValue;
        var cNew;
        switch(change.type) {
          case 'add':
          case 'update':
            cNew = obj[change.name];
          break;
          case 'splice':
            cPath = (path ? path+'.' : '')+change.index;
            if(change.removed.length) {
              console.log(change);
              cType = 'remove';
              cOld = change.removed[0];
              if(change.removed.length > 1) {
                changes.push({
                  addedCount: change.addedCount,
                  index: change.index + 1,
                  object: change.object,
                  removed: change.removed.slice(1),
                  type: change.type
                });
              }
            } else if(change.addedCount) {
              cType = 'add';
              cNew = obj[change.index];
              if(change.addedCount > 1) {
                changes.push({
                  addedCount: change.addedCount - 1,
                  index: change.index + 1,
                  object: change.object,
                  removed: change.removed,
                  type: change.type
                });
              }
            } else {
              cType = 'update';
              cOld = change.removed[0];
              cNew = obj[change.index];
            }
          break;
        }
        if(typeof cNew === "object") {
          iterator(cNew, cb, cPath);
        }
        cb(cPath, cType, cNew, cOld);
      }
    });
  }
  iterator(obj, cb);
}

var model2 = {
  a:{
    b:1,
    d:[1,2,{
      test:'hello',
      carrot: 123
    }]
  },
  c:2
};
pathObserver(model2, function(path, action, newValue, oldValue) {
  console.log('path: ' + path, 'action: ' + action, 'new: ' + JSON.stringify(newValue), 'old: ' + JSON.stringify(oldValue));
});