SOURCE

const arr = [
    ['a', 'b', 'c'],
    ['a', 'd'],
    ['d', 'e'],
    ['f', 'g'],
    ['f', 'a'],
    ['h', 'g'],
    ['i']
]

function test(arr) {
    const r = []

    arr = arr.map(item => item.sort()).sort()
    console.log(arr)

    arr.forEach(item => {
        if (r.length === 0) {
            r.push(item)
        } else {
            const index = r.length - 1;
            let before = r[index];
            const flag = before.some(b => item.includes(b));
            if (flag) {
                before = Array.from(new Set([...before, ...item]))
                r.splice(index, 1, before)
            } else {
                r.push(item)
            }
        }
    })
    
    return r
}

console.log(test(arr))