08RxJS错误处理操作符

• 默认的error

of(1, 2, 3, 4, 5).pipe(
  map(
    n => {
      if (n === 4) {
        throw new Error('four err')
      }
      return n;
    }
  )
).subscribe(
  x => console.log(x),
  error => console.error('err', error),
  () => console.log('complete')
)
//1
//2
//3
//four err

catchError

无视错误，返回新的Observable

of(1, 2, 3, 4, 5).pipe(
  map(
    n => {
      if (n === 4) {
        throw new Error('four err')
      }
      return n;
    } 
  ),
  catchError(err => of('捕获错误')),
).subscribe(
  x => console.log(x),
  error => console.error('err', error),
  () => console.log('complete')
)
//1
//2
//3
//捕获错误
//complete

• 重试错误

捕获到错误时，重试时要加take，否则会报错Maximum call stack size exceeded

of(1, 2, 3, 4, 5).pipe(
  map(
    n => {
      if (n === 4) {
        throw new Error('four err')
      }
      return n;
    }
  ),
  catchError((err, caught) => caught),
  take(30)
).subscribe(
  x => console.log(x),
  error => console.error('err', error),
  () => console.log('complete')
)

retry

发生错误后重试指定次数

of(1, 2, 3, 4, 5).pipe(
  map(
    n => {
      if (n === 4) {
        throw new Error('four err')
      }
      return n;
    }
  ),
  retry(2)
).subscribe(
  x => console.log(x),
  error => console.error('err', error),
  () => console.log('complete')
)

retryWhen

发生错误后，自定义重试策略，参数是个回调函数，返回Observalbe

const source = interval(1000)
const example = source.pipe(
  map(val => {
    if (val > 5) {
    //错误由retryWhen接收
      throw val;
    }
    return val;
  }),
  retryWhen(errors =>
    errors.pipe(
      tap(val => console.log(`${val}太大了`)),
      delay(3000)
    )
  )
)
const subscribe = example.subscribe(
  val => console.log(val),
  error => console.error('err ', error)
)
// 1 2 3 4 5 6太大了（延迟3秒后重试）