MakeSchema

function makeSchema(x) {
  if (Array.isArray(x)) return x.map(k => makeSchema(k));
  else if (typeof x === 'boolean') return true;
  else if (typeof x === 'number') return 1;
  else if (typeof x === 'string') return 'string';
  else if (typeof x === 'object') {
    let obj = {};
    for (let k in x) {
      obj[k] = makeSchema(x[k]);
    }
    return obj;
  }
}

wesh

function makeBetterSchema(x) {
  switch (typeof x) {
    case 'boolean': return true
    case 'number': return 1
    case 'string': return 'string'
    case 'object': {
      return Array.isArray(x)
        ? x.map(makeBetterSchema)
        : Object.keys(x).reduce((acc, k) => ({ ...acc, [k]: makeBetterSchema(x[k])}), {})
    }
  }
}

Wesh

function makeSchema(x) {
  if (Array.isArray(x)) {
    x = x.map(k => makeSchema(k));
    if (!x.some(e => e !== 'string')) x = ['string'];
    return x;
  } else {
    let type = typeof x;
    if (type === 'boolean') return true;
    else if (type === 'number') return 1;
    else if (type === 'string') return 'string';
    let obj = {};
    for (let k in x) {
      obj[k] = makeSchema(x[k]);
    }
    return obj;
  }
}