Object being recognized as null or undefined-CodePudding

I'm trying to assign housePrototype as the prototype of House object, and followed up with this error

Object.assign(House.prototype, this.housePrototype); ^ TypeError: Cannot convert undefined or null to object

What am I doing wrong?

const House = {
    name: 'houseObject',
     readLocation: (location)=>{
      console.log(`house is located at ${location}`)
    }
  }

  const housePrototype = {
    readLocation: (location) => {
    console.log(`house prototype is located at ${location}`)
    }
  }

  Object.assign(House.prototype, housePrototype)
  
  House.readLocation('Malabe');
  console.log(House);

CodePudding user response：

All credit goes to @JaromandaX. He explained me the issue in the comments of the question.

Even though functions are Objects in JavaScript the are NOT identical. To access the prototype of a function function() {}.prototype can be used. But in the question it is trying to access the prototype of a regular-object not a function-object. Which is undefined, thus the error.

Object.assign(House.__proto__, housePrototype);

With this it is possible to assign desired object to the prototype (though it's not common to use proto according to some articles)

Solution code would be

const House = {
    name: 'houseObject',
     readLocation: (location)=>{
      console.log(`house is located at ${location}`)
    }
  }

  const housePrototype = {
    readLocation: (location) => {
    console.log(`house prototype is located at ${location}`)
    }
  }

  Object.assign(House.__proto__, housePrototype)
  
  House.readLocation('Malabe');

I found a complete description in following stackoverflow thread __proto__ VS. prototype in JavaScript

CodePudding user response：

Hey Bro the problem is House.prototpe because the object house has no object called prototype there are only two name and readLocation so change code to this : from this :

const House = {
    name: 'houseObject',
     readLocation: (location)=>{
      console.log(`house is located at ${location}`)
    }
  }

  const housePrototype = {
    readLocation: (location) => {
    console.log(`house prototype is located at ${location}`)
    }
  }

  Object.assign(House.prototype, housePrototype)
  
  House.readLocation('Malabe');
  console.log(House);

to this :

const House = {
    name: 'houseObject',
     readLocation: (location)=>{
      console.log(`house is located at ${location}`)
    }
  }

  const housePrototype = {
    readLocation: (location) => {
    console.log(`house prototype is located at ${location}`)
    }
  }

  Object.assign(House, housePrototype)
  
  House.readLocation('Malabe');
  console.log(House);

CodePudding user response：

Usefull docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#try_it

const House = {
  name: 'houseObject',
  readLocation: (location)=>{
    console.log(`house is located at ${location}`)
  }
}

const housePrototype = {
  readLocation: (location) => {
    console.log(`house prototype is located at ${location}`)
  }
}

//Object.assign(target, src);
Object.assign(House, housePrototype);

House.readLocation('Malabe');
console.log(House);