How can I do a shallow comparison of the properties of two objects with Javascript or lodash?

Simple ES6 approach:

const shallowCompare = (obj1, obj2) =>
  Object.keys(obj1).length === Object.keys(obj2).length &&
  Object.keys(obj1).every(key => obj1[key] === obj2[key]);

Here I added the object keys amount equality checking for the following comparison should fail (an important case that usually does not taken into the account):

shallowCompare({ x: 1, y: 3}, { x: 1, y: 3, a: 1}); // false

2019 Update. Per Andrew Rasmussen’ comment we also need to take into account undefined case. The problem with the previous approach is that the following comparison returns true:

({ foo: undefined })['foo'] === ({ bar: undefined })['foo'] // true

So, explicit keys existence check is needed. And it could be done with hasOwnProperty:

const shallowCompare = (obj1, obj2) =>
  Object.keys(obj1).length === Object.keys(obj2).length &&
  Object.keys(obj1).every(key => 
    obj2.hasOwnProperty(key) && obj1[key] === obj2[key]
  );