React propTypes: objectOf vs shape?

What's the difference between PropTypes.objectOf and PropTypes.shape? In the PropTypes:

// An object with property values of a certain type
optionalObjectOf: PropTypes.objectOf(PropTypes.number)

vs

// An object taking on a particular shape
optionalObjectWithShape: PropTypes.shape({
  color: PropTypes.string,
  fontSize: PropTypes.number
})

When should I use objectOf and when should I use shape?

PropTypes.objectOf is used when describing an object whose properties are all the same type.

    const objectOfProp = {
        latitude: 37.331706,
        longitude: -122.030783
    }
    // PropTypes.objectOf(PropTypes.number)

PropTypes.shape is used when describing an object whose keys are known ahead of time, and may represent different types.

    const shapeProp = {
        name: 'Jane',
        age: 25
    }
    // PropTypes.shape({ name: PropTypes.string, age: PropTypes.number })

Just wanted to provide an example given the following object:

{
    petStore: {
        animals: {
           '23': { name: 'Snuffles', type: 'dog', age 13 }
           '29': { name: 'Mittens', type: 'cat', age: 7 }
        }
    }
}

ObjectOf and Shape

Used when an object could have different property names, but a consistent set of properties for each one:

const animalItemShape = {
    name: PropTypes.string,
    type: PropTypes.string,
    age: PropTypes.number
}

const petStoreShape = {
    animals: PropTypes.objectOf(PropTypes.shape(animalItemShape))
}

As you can see, animals is an object composed of multiple properties that each conform to the animalItemShape type.

Hope it helps!