javascript - setInterval 永远不会在函数中触发，并且不知道为什么( Angular )

Question

我有这个函数，由于某种原因，它直接从打印“在 jobstart 调用后提交组件行”到“进入 while 循环”:

returned() {
    this.numReturned++;
    if (this.numReturned !== this.numSubmitting) {
        return;
    }
    console.log('submit component line before jobstart call');
    this.submitService.startJobToAuditTable().subscribe();
    console.log('submit component line after jobstart call');

    let timer = setInterval(() => {
        console.log('start of interval');
        this.submitService.checkIfJobRunning().subscribe(res => {
            console.log("res from job running check is " + res);
            this.jobFinished = res;
        });

        this.submitService.pollAuditTable().subscribe(res => {
            console.log("res from audit table:\n\t" + res);
            this.auditRows = res;
        });
    }, 10000);  //runs every 10 seconds. will be longer after testing

    console.log('entering while loop');
    while (this.jobFinished === false) {

    }

    console.log('clearing interval, job should be finished now');
    clearInterval(timer);
    return;
}

console.log 和 setInterval 内的其他内容永远不会被调用，我很困惑为什么会这样

Answer 1

您的 while 循环正在消耗执行并阻塞一切。如果您想等到作业完成而不是 while(done){} 循环，您可以返回一个 promise :

returned() {
  return new Promise((resolve, reject) => {
      this.numReturned++;
      if (this.numReturned !== this.numSubmitting) {
          resolve();
          return;
      }
      console.log('submit component line before jobstart call');
      this.submitService.startJobToAuditTable().subscribe();
      console.log('submit component line after jobstart call');

      let timer = setInterval(() => {

          console.log('start of interval');
          this.submitService.checkIfJobRunning().subscribe(res => {
              console.log("res from job running check is " + res);
              this.jobFinished = res;
          });

          this.submitService.pollAuditTable().subscribe(res => {
              console.log("res from audit table:\n\t" + res);
              this.auditRows = res;
          });

-->       if(this.jobFinished === false) {
              console.log('clearing interval, job should be finished now');
              clearInterval(timer);
              resolve();
          }

      }, 10000);  //runs every 10 seconds. will be longer after testing

  }
}

在异步代码中，使用

resolve() 代替 return。

稍后，当您调用此函数时，如果您想等到作业完成，可以使用 await 关键字

await returned ();  // will wait until resolve() is called
// code after all jobs done

或者如果异步/等待不是首选:

returned().then(() => {
    // code after all jobs done
})