typed-task-log

typed-task-log is a task-oriented event emitter to facilitate logging with context.

Install

npm install typed-task-logger

or

yarn add typed-task-logger

Usage

See usage examples from the tests.

Full example

type TaskMeta = {
  readonly parentTaskId: null | string;
  readonly label: string;
  readonly kind: "add" | "mult";
};

let nextId = 0;
const taskLog = new TaskLog<TaskMeta>({
  createUniqueId: () => `${nextId++}`,
  performanceNow: () => performance.now(),
});

const history: TaskEvent<TaskMeta>[] = [];
taskLog.addListener((event) => history.push(event));

const value = await taskLog.task(
  { parentTaskId: null, label: "task 1", kind: "add" },
  async (parentTaskId) => {
    await new Promise((resolve) => setTimeout(resolve, 100));
    return (
      (await taskLog.task(
        { parentTaskId, label: "childAdd", kind: "add" },
        async () => 1 + 4,
      )) +
      (await taskLog.task(
        { parentTaskId, label: "childMult", kind: "mult" },
        async () => 5 * 3,
      ))
    );
  },
);

taskLog.removeAllListeners();

expect(value).toEqual(20);

expect(history).toEqual([
  {
    taskId: "0",
    kind: "begin",
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    meta: { parentTaskId: null, label: "task 1", kind: "add" },
  },
  {
    taskId: "1",
    kind: "begin",
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    meta: { parentTaskId: "0", label: "childAdd", kind: "add" },
  },
  {
    taskId: "1",
    meta: { parentTaskId: "0", label: "childAdd", kind: "add" },
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    duration: expect.any(Number),
    kind: "end",
    result: { kind: "value", value: 5 },
  },
  {
    taskId: "2",
    kind: "begin",
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    meta: { parentTaskId: "0", label: "childMult", kind: "mult" },
  },
  {
    taskId: "2",
    meta: { parentTaskId: "0", label: "childMult", kind: "mult" },
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    duration: expect.any(Number),
    kind: "end",
    result: { kind: "value", value: 15 },
  },
  {
    taskId: "0",
    meta: { parentTaskId: null, label: "task 1", kind: "add" },
    timestamp: expect.any(Number),
    performanceNow: expect.any(Number),
    duration: expect.any(Number),
    kind: "end",
    result: { kind: "value", value: 20 },
  },
]);