SOURCE

function Fruit() {
    let _skillLevel = 0;
    Object.defineProperty(this, 'skillLevel', {
        get: () => {
            console.log('get')
            return _skillLevel;
        },
        set: value => {
            console.log('set', value)
            _skillLevel = value
        }
    })
}

const fruit = new Fruit();

console.log(fruit.skillLevel);
fruit.skillLevel = 2;
console.log(fruit.skillLevel);