HTMLify

const { body } = document;

let zoomActivated = false;

window.addEventListener('keydown', (e) => {
	if(e.key === 'z') {
		zoomActivated = !zoomActivated;
	}
});

window.addEventListener('click', () => {
    zoomActivated = !zoomActivated;
});

window.addEventListener('mousemove', (e) => {
	const { clientX: x, clientY: y } = e;
	
	if(zoomActivated) {
		body.style.transform = 'scale(2)';
		body.style.transformOrigin = `${x}px ${y}px`;
	} 
    else {
		body.style.transform = 'none';
	}
});