在运行时从数组值的可观察对象派生Union类型

import { Observable } from 'rxjs';

const observableArray = new Observable<number[]>(subscriber => {
  // 在这里异步获取数组值，例如从服务器获取
  const array = [1, 2, 3];
  subscriber.next(array);
  subscriber.complete();
});

observableArray.subscribe(array => {
  // 在这里对数组值进行处理
  const unionType = getUnionType(array);
  console.log(unionType);
});

function getUnionType(array: number[]): number | string {
  let unionType: number | string;
  if (array.length > 0) {
    if (typeof array[0] === 'number') {
      unionType = array[0];
    } else if (typeof array[0] === 'string') {
      unionType = array[0];
    } else {
      unionType = null;
    }
  } else {
    unionType = null;
  }
  return unionType;
}