Copy your when2meet responses from one when2meet to another.

when2meet-copier.user.js

// ==UserScript==
// @name         When2meet Copy-Paste
// @match        https://www.when2meet.com/?*
// @version      2024-03-06
// @description  Copy your when2meet responses from one when2meet to the other.
// @author       AbyxDev
// @icon         https://www.google.com/s2/favicons?sz=64&domain=when2meet.com
// @grant        none
// @updateURL    https://gist.github.com/Kenny2github/c614b71dd67a5e80abcadfab3e54b4f0/raw/when2meet-copier.user.js
// @downloadURL  https://gist.github.com/Kenny2github/c614b71dd67a5e80abcadfab3e54b4f0/raw/when2meet-copier.user.js
// ==/UserScript==

/**
 * Usage:
 * 1. Open the source when2meet, SIGN IN, and click "Copy".
 * 2. Your responses will be put in your clipboard.
 * 3. Open the destination when2meet, SIGN IN, and click "Paste".
 * 4. Your responses will OVERWRITE the destination when2meet.
 */
// declare const TimeOfSlot: number[]
// declare const AvailableAtSlot: number[][]
// declare const UserID: number
// declare const SelectFromHere: (x: {target: HTMLElement | null}) => void
// declare const SelectToHere: (x: {target: HTMLElement | null}) => void
// declare const SelectStop: () => void

(() => {
	if (!navigator.clipboard) return;
	async function doCopy() {
		const times = [];
		for (let slot = 0; slot < TimeOfSlot.length; ++slot) {
			if (AvailableAtSlot[slot].includes(UserID)) times.push(TimeOfSlot[slot]);
		}
		await navigator.clipboard.writeText('' + times);
		alert(`Copied ${times.length} available timeslots`);
	}
	async function doPaste() {
		const timesText = await navigator.clipboard.readText();
		if (!timesText.match(/^\d+(?:,\d+)*$/)) {
			alert('No timeslots in clipboard');
			return;
		}
		const times = new Set(timesText.split(',').map(x => +x));
        let elem = null;
		let filled = false;
		for (let slot = 0; slot < TimeOfSlot.length; ++slot) {
			const us = times.has(TimeOfSlot[slot]);
			const them = AvailableAtSlot[slot].includes(UserID);
			const slotElem = document.getElementById('YouTime' + TimeOfSlot[slot]);
			let updated = false;
			if (us === them && elem !== null) {
				// already desired state and dragging something
				if (filled === us) {
					// already dragging desired state, continue
					elem = slotElem;
				} else {
					// currently dragging undesired state, stop
					SelectToHere({target: elem});
					SelectStop();
					elem = null;
					updated = true;
				}
			} else if (elem !== null) {
				// state needs changing and dragging something
				if (filled === us) {
					// already dragging desired state, continue
					elem = slotElem;
				} else {
					// currently dragging undesired state, switch
					SelectToHere({target: elem});
					SelectStop();
					elem = slotElem;
					filled = us;
					SelectFromHere({target: elem});
					updated = true;
				}
			} else if (us !== them) {
				// state needs changing and not dragging, start
				elem = slotElem;
				filled = us;
				SelectFromHere({target: elem});
				updated = true;
			} // else, already desired state and not dragging
			if (slotElem.parentElement.matches(':last-child') && !updated) {
				// end of column, must stop
				SelectToHere({target: slotElem});
				SelectStop();
				elem = null;
			}
		}
		if (elem !== null) {
			SelectToHere({target: elem});
			SelectStop();
			elem = null;
		}
	}

	const copy = document.createElement('button');
	copy.innerText = 'Copy';
	copy.addEventListener('click', doCopy);
	const paste = document.createElement('button');
	paste.innerText = 'Paste';
	paste.addEventListener('click', doPaste);
	document.getElementById('UserName').parentElement.appendChild(copy);
	document.getElementById('UserName').parentElement.appendChild(paste);
})();