Angular

Question

我正在调用一个需要一些时间才能解决的可观察对象，我添加了一个条件来检查我们是否得到了有效结果（它工作正常但在我看来不应该这样做).

代码：

this.store.select(state => this.list = state.list)
  .subscribe(result => {
    //Without checking if result exists, it throws here undefined, only solution found so far is to add the check below
    if (result) {
     console.log('result is loaded');

      this.copyOfList = [...this.list];
      for (const item of result) {
        this.itemCategories(item.category);
      }
    }
  });

Answer 1

您可以使用 skipWhile:

this.store.select(state => this.list = state.list).pipe(skipWhile(x => !!x))
  .subscribe(result => {

  });

Answer 2

我更喜欢filter

this.store.select(state => this.list = state.list)
    .pipe(filter(x => !!x))
    .subscribe();

我更喜欢这个主要是因为 array.filter 方法的相似性。

Angular - 检查是否加载了 observable

Angular - Check if observable is loaded or not

javascript

typescript

ngxs