我从Angular页面复制了一些代码，可视化代码显示错误：
此行的错误：

map((e: KeyboardEvent) => e.target.value),

错误

Property 'value' does not exist on type 'EventTarget'.

Angular website代码：

import { fromEvent } from 'rxjs';
import { ajax } from 'rxjs/ajax';
import { map, filter, debounceTime, distinctUntilChanged, switchMap } from 'rxjs/operators';

const searchBox = document.getElementById('search-box');

const typeahead = fromEvent(searchBox, 'input').pipe(
  map((e: KeyboardEvent) => e.target.value),
  filter(text => text.length > 2),
  debounceTime(10),
  distinctUntilChanged(),
  switchMap(() => ajax('/api/endpoint'))
);

typeahead.subscribe(data => {
 // Handle the data from the API
});