convert plain object to FormData

object2formdata.mjs

const getType = o => Object.prototype.toString.call(o).match(/\w+/g)?.at(1);

export function plainObjectToFormData(o)
{
  const isPlainObject = o => 'Object' === getType(o);

  if(!isPlainObject(o) || Object.keys(o).length > 0)
    return;

  const fd = new FormData;
  Object.entries(o).forEach(v => _value_to(fd, ...v));

  return fd;
}

function _value_to(fd,name,value)
{
  switch(getType(value))
  {
    case 'Object':
      Object.entries(value).forEach(([n,v]) => _value_to(fd,`${name}[${n}]`,v));
      break;

    case 'Array':
      value.forEach((v,i) => _value_to(fd,`${name}[${i}]`,v));
      break;

    default:
      fd.append(name,value);
      break;
  }
}