@variantjs/core/src/__tests__/throttle.test.ts

VariantJS common functions and utilities

import throttle from '../helpers/throttle';

describe('throttle', () => {
  it('runs the method after 200 ms by default', () => {
    const mockFn = jest.fn();

    jest.useFakeTimers();

    const throttledFn = throttle(mockFn);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(1);

    jest.advanceTimersByTime(199);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(1);

    jest.advanceTimersByTime(1);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(2);
  });

  it('runs the method inmediatly once', () => {
    const mockFn = jest.fn();

    jest.useFakeTimers();

    const throttledFn = throttle(mockFn, 300);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(1);

    jest.advanceTimersByTime(299);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(1);

    jest.advanceTimersByTime(1);

    throttledFn();

    expect(mockFn).toHaveBeenCalledTimes(2);
  });
});