dragon-recurse.js

const getDragon2 = n => {
    const getDragonRecurse = (n, complement) => {
        if(n === 1) {
            return complement ? [0] : [1]
        }
        
        const right = getDragonRecurse(n - 1, complement);
        const left = getDragonRecurse(n - 1, !complement);
        return complement ? [...right, 0, ...left] : [...left, 1, ...right]
    }

    return getDragonRecurse(n, false).join('')
}

const n = 4;
console.log(getDragon2(n))