I’m trying to understand behavior of function composition in javascript.
const Animal = (name) => {
let properties = { name };
return ({
get name() { return properties.name },
set name(newName) { properties.name = newName },
breathe: function() {console.log(`${this.name} breathes!`); }
})
}
const aquaticKind = (animal) => ({
swim: () => console.log(`${animal.name} swims`)
})
const walkingKind = (animal, noOfLegs) => {
const properties = { noOfLegs }
return ({
get noOfLegs() { return properties.noOfLegs },
set noOfLegs(n) { properties.noOfLegs = n; },
walk: () => console.log(`${animal.name} walks with ${properties.noOfLegs} legs`)
})
}
const egglayingKind = (animal) => ({
layEgg: () => console.log(`${animal.name} laid an egg`)
})
const Crocodile = (name) => {
const info = Animal(name);
return Object.assign(info,
walkingKind(info, 4),
aquaticKind(info),
egglayingKind(info)
);
}
const snooty = Crocodile('snooty');
snooty.breathe();
snooty.swim();
snooty.walk();
snooty.name = "coolie";
snooty.noOfLegs = 23 // I expected this to get update to 23
snooty.swim();
snooty.walk();
snooty.layEgg();
If you run the code above, you will see that noOfLegs
never get updated, while name
get updated. I can’t seem to wrap my head around this. How do we make noOfLegs
get updated too?