I have been reading about composition but every tutorial I see does something similar to the following.
const eater = (state) => ({
eat(amount) {
console.log(`${state.name} is eating.`)
state.energy += amount
}
});
function Dog(name, energy, breed) {
let dog = {
name,
energy,
breed,
}
return Object.assign(
dog,
eater(dog),
sleeper(dog),
player(dog),
barker(dog),
)
}
const leo = Dog('Leo', 10, 'Goldendoodle')
leo.eat(10) // Leo is eating
leo.bark() // Woof Woof!Why do we need the Eater function to return the function we want to add as a property?
By extension, why do we need to send the object we want the method to be added to?
why not do something like the following?
const eat = (amount) => {
console.log(`${this.name} is eating.`)
this.energy += amount
}
function Dog(name, energy, breed) {
let dog = {
name,
energy,
breed,
}
return Object.assign(
dog, {
eat
}, {
sleep
}, {
play
}, {
bark
}
)
}
const leo = Dog('Leo', 10, 'Goldendoodle')
leo.eat(10) // Leo is eating
leo.bark() // Woof Woof!