You could use Object.assign.
var a = { fruit: "apple" },
b = { vegetable: "carrot" },
food = Object.assign({}, a, b);
console.log(food);For browser without supporting Object.assign, you could iterate the properties and assign the values manually.
var a = { fruit: "apple" },
b = { vegetable: "carrot" },
food = [a, b].reduce(function (r, o) {
Object.keys(o).forEach(function (k) { r[k] = o[k]; });
return r;
}, {});
console.log(food);