const url = 'https://zh.wikipedia.org/w/api.php?action=opensearch&format=json&limit=5&origin=*';

​

const getSuggestList = (keyword) => fetch(url + '&search=' + keyword, { method: 'GET', mode: 'cors' })

                                    .then(res => res.json())

​

const searchInput = document.getElementById('search');

const suggestList = document.getElementById('suggest-list');

​

const keyword = Rx.Observable.fromEvent(searchInput, 'input');

const selectItem = Rx.Observable.fromEvent(suggestList, 'click');

​

const render = (suggestArr = []) => suggestList.innerHTML = suggestArr.map(item => '<li>'+ item +'</li>').join('')

​

keyword

  .switchMap(

    e => getSuggestList(e.target.value),

    (e, res) => res[1]

  )

  .subscribe(list => render(list))

​

selectItem

  .filter(e => e.target.matches('li'))

  .map(e => e.target.innerText)

  .subscribe(text => { 

      searchInput.value = text;

      render();

  })