Node.js library for periodical tasks written in Typescript.
npm install @1999/scheduler --save
The only concept of scheduler is a Task which represents a periodically run task. It should be a callback which should return a Promise.
Use scheduler.addTask(task: Task, period: number) function to set up task period.
import {
default as Scheduler,
Task,
} from '@1999/scheduler';
const task: Task = () => Promise.resolve(2);
const scheduler = new Scheduler();
scheduler.addTask(task, 1000);
scheduler.start();In this case you can pass task groups in scheduler constructor. Then use scheduler.addTask(task: Task, periodId: string) function to assign task to task group.
import {
default as Scheduler,
Task,
} from '@1999/scheduler';
const task1: Task = () => got('https://api.facebook/id/1');
const task2: Task = () => got('https://api.facebook/id/2');
const scheduler = new Scheduler({ api: 1000 });
scheduler.addTask(task1, 'api');
scheduler.addTask(task2, 'api');
scheduler.start();Sometimes it's not enough to have execution periodicity for tasks. For instance when you have an API which allows you to make requests once per N seconds: in this case it can be safer to send next request only N seconds after you get the response from the previous request. For this purpose you can use Marker callback which is the only argument for Task:
import {
default as Scheduler,
Marker,
Task,
} from '@1999/scheduler';
const task: Task = (marker: Marker) => {
return got('https://api.facebook/id/1').then(() => {
// you can run marker function anywhere inside your task
// and the period pause will be started from this moment
marker();
});
};
const scheduler = new Scheduler();
scheduler.addTask(task);
scheduler.start();Scheduler instance extends node.js EventEmitter. You can use it to subscribe to events happening inside Scheduler instance:
taskCompleted- emits when task is successfully finished. Also emits an object{ name: string, execTime: number }where runTime is the task execution time in milliseconds.taskFailed- emits when task execution fails. Also emits an object{ err: Error, execTime: number, name: string }
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