fake-mouse-event

Fake mouse event generator with x/y properties for jsdom.

Why

jsdom's MouseEvent constructor does not properly set coordinate properties such as x, y, offsetX, and offsetY. This library provides synthetic MouseEvent and PointerEvent instances with correct coordinate values for testing event-driven code in jsdom environments.

Installation

npm i @masatomakino/fake-mouse-event -D

Usage

Factory Functions

Use getMouseEvent and getPointerEvent to create events with sensible defaults.

import { getMouseEvent, getPointerEvent } from "@masatomakino/fake-mouse-event";

// Basic mouse event (all coordinates default to 0)
const click = getMouseEvent("click");

// Mouse event with custom coordinates
const clickAt = getMouseEvent("click", {
  x: 100,
  y: 100,
  offsetX: 150,
  offsetY: 150,
});

// Pointer event
const pointerDown = getPointerEvent("pointerdown", {
  x: 100,
  y: 100,
  pointerId: 1,
});

Dispatching Events

Created events can be dispatched to DOM elements as usual.

const canvas = document.createElement("canvas");
canvas.addEventListener("click", (e) => {
  console.log(e.x, e.y); // 100, 100
});

const event = getMouseEvent("click", { x: 100, y: 100 });
canvas.dispatchEvent(event);

API

getMouseEvent(type, options?)

Returns a FakeMouseEvent instance (extends UIEvent, implements MouseEvent).

Defaults: bubbles: true, cancelable: true, all coordinates: 0.

getPointerEvent(type, options?)

Returns a FakePointerEvent instance (extends FakeMouseEvent).

Additional defaults: pointerId: 0, pointerType: "mouse", isPrimary: true.

FakeMouseEventInit

Extends UIEventInit. Key properties:

| Category | Properties | | --- | --- | | Coordinates | x, y, clientX, clientY, screenX, screenY, offsetX, offsetY, pageX, pageY | | Modifiers | altKey, ctrlKey, shiftKey, metaKey | | Button | button, buttons | | Movement | movementX, movementY |

FakePointerEventInit

Extends FakeMouseEventInit. Additional properties:

pointerId, width, height, pressure, tangentialPressure, tiltX, tiltY, twist, pointerType, isPrimary

License

MIT