Backbone.Collection#update

gistfile1.js

Backbone.Collection.prototype.update = function(collection) {
  var _ids = _(collection)
    .chain()
    .reduce(function(ids, model) {
        var
          id = model.id
          ,needle = this.get(id)
        ;

        if (needle) {
          needle.set(model);
        }
        else {
          this.add(model);
        }

        return ids.concat(model.id);
      }
      ,[]
      ,this
    )
  ;

  this.remove(this.reject(function(model) {
    return _ids.include(model.id);
  }));
};