headlessui/packages/@headlessui-react/pages/listbox/multiple-elements.tsx

import * as React from 'react'
import { Listbox } from '@headlessui/react'

function classNames(...classes) {
  return classes.filter(Boolean).join(' ')
}

const people = [
  'Wade Cooper',
  'Arlene Mccoy',
  'Devon Webb',
  'Tom Cook',
  'Tanya Fox',
  'Hellen Schmidt',
  'Caroline Schultz',
  'Mason Heaney',
  'Claudie Smitham',
  'Emil Schaefer',
]

export default function Home() {
  return (
    <div className="flex justify-center w-screen h-full p-12 space-x-4 bg-gray-50">
      <PeopleList />

      <div>
        <label htmlFor="email" className="block text-sm font-medium leading-5 text-gray-700">
          Email
        </label>
        <div className="relative mt-1 rounded-md shadow-sm">
          <input
            className="block w-full form-input sm:text-sm sm:leading-5"
            placeholder="you@example.com"
          />
        </div>
      </div>

      <PeopleList />
    </div>
  )
}

function PeopleList() {
  const [active, setActivePerson] = React.useState(people[2])

  // Choose a random person on mount
  React.useEffect(() => {
    setActivePerson(people[Math.floor(Math.random() * people.length)])
  }, [])

  return (
    <div className="w-64">
      <div className="space-y-1">
        <Listbox
          value={active}
          onChange={value => {
            console.log('value:', value)
            setActivePerson(value)
          }}
        >
          <Listbox.Label className="block text-sm font-medium leading-5 text-gray-700">
            Assigned to
          </Listbox.Label>

          <div className="relative">
            <span className="inline-block w-full rounded-md shadow-sm">
              <Listbox.Button className="relative w-full py-2 pl-3 pr-10 text-left transition duration-150 ease-in-out bg-white border border-gray-300 rounded-md cursor-default focus:outline-none focus:shadow-outline-blue focus:border-blue-300 sm:text-sm sm:leading-5">
                <span className="block truncate">{active}</span>
                <span className="absolute inset-y-0 right-0 flex items-center pr-2 pointer-events-none">
                  <svg
                    className="w-5 h-5 text-gray-400"
                    viewBox="0 0 20 20"
                    fill="none"
                    stroke="currentColor"
                  >
                    <path
                      d="M7 7l3-3 3 3m0 6l-3 3-3-3"
                      strokeWidth="1.5"
                      strokeLinecap="round"
                      strokeLinejoin="round"
                    />
                  </svg>
                </span>
              </Listbox.Button>
            </span>

            <div className="absolute w-full mt-1 bg-white rounded-md shadow-lg">
              <Listbox.Options className="py-1 overflow-auto text-base leading-6 rounded-md shadow-xs max-h-60 focus:outline-none sm:text-sm sm:leading-5">
                {people.map(name => (
                  <Listbox.Option
                    key={name}
                    value={name}
                    className={({ active }) => {
                      return classNames(
                        'relative py-2 pl-3 cursor-default select-none pr-9 focus:outline-none',
                        active ? 'text-white bg-indigo-600' : 'text-gray-900'
                      )
                    }}
                  >
                    {({ active, selected }) => (
                      <>
                        <span
                          className={classNames(
                            'block truncate',
                            selected ? 'font-semibold' : 'font-normal'
                          )}
                        >
                          {name}
                        </span>
                        {selected && (
                          <span
                            className={classNames(
                              'absolute inset-y-0 right-0 flex items-center pr-4',
                              active ? 'text-white' : 'text-indigo-600'
                            )}
                          >
                            <svg className="w-5 h-5" viewBox="0 0 20 20" fill="currentColor">
                              <path
                                fillRule="evenodd"
                                d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z"
                                clipRule="evenodd"
                              />
                            </svg>
                          </span>
                        )}
                      </>
                    )}
                  </Listbox.Option>
                ))}
              </Listbox.Options>
            </div>
          </div>
        </Listbox>
      </div>
    </div>
  )
}