map function for objects (instead of arrays)

Question

I have an object:

myObject = { \'a\': 1, \'b\': 2, \'c\': 3 }

I am looking for a native method, similar to Array.prototype.map

Answer 1

Define a function mapEntries.

mapEntries takes a callback function that is called on each entry in the object with the parameters value, key and object. It should return the a new value.

mapEntries should return a new object with the new values returned from the callback.

Object.defineProperty(Object.prototype, 'mapEntries', {
  enumerable: false,
  value: function (mapEntriesCallback) {
    return Object.fromEntries(
      Object.entries(this).map(
        ([key, value]) => [key, mapEntriesCallback(value, key, this)]
      )
    )
  }
})


// Usage example:

var object = {a: 1, b: 2, c: 3}
var newObject = object.mapEntries(value => value * value)
console.log(newObject)
//> {a: 1, b: 4, c: 9}

Edit: A previous version didn't specify that this is not an enumerable property