mapExtend.js

  // maps extend across many objects
  _.mapExtend = function(array) {
    var sources = slice.call(arguments, 1);
    sources.unshift({});
    var source = _.extend.apply(this, sources); // combine sources
    each(array, function(obj) {
      for (var prop in source) {
        obj[prop] = source[prop];
      }
    });
    return array;
  };
  
  test("mapExtend", function() {
   var objects = [{text: 'foo', id: 1}, {text: 'bar', id: 5}];
   equal(_.mapExtend(objects, {text: 'mapExtend!'}), [{text: 'mapExtend!', id: 1}, {text: 'mapExtend!', id: 5}], 'mapExtend takes one source');
   equal(_.mapExtend(objects, {text: 'mapExtend!'}, {id: 2}), [{text: 'mapExtend!', id: 2}, {text: 'mapExtend!', id: 2}], 'mapExtend takes many sources');
  });