Function _prepareGroup

src/Sortable.js:247–287

(options)

	},

	_prepareGroup = function (options) {
		function toFn(value, pull) {
			return function(to, from, dragEl, evt) {
				let sameGroup = to.options.group.name &&
								from.options.group.name &&
								to.options.group.name === from.options.group.name;

				if (value == null && (pull || sameGroup)) {
					// Default pull value
					// Default pull and put value if same group
					return true;
				} else if (value == null || value === false) {
					return false;
				} else if (pull && value === 'clone') {
					return value;
				} else if (typeof value === 'function') {
					return toFn(value(to, from, dragEl, evt), pull)(to, from, dragEl, evt);
				} else {
					let otherGroup = (pull ? to : from).options.group.name;

					return (value === true ||
					(typeof value === 'string' && value === otherGroup) ||
					(value.join && value.indexOf(otherGroup) > -1));
				}
			};
		}

		let group = {};
		let originalGroup = options.group;

		if (!originalGroup || typeof originalGroup != 'object') {
			originalGroup = {name: originalGroup};
		}

		group.name = originalGroup.name;
		group.checkPull = toFn(originalGroup.pull, true);
		group.checkPut = toFn(originalGroup.put);
		group.revertClone = originalGroup.revertClone;

		options.group = group;
	},

	_hideGhostForTarget = function() {
		if (!supportCssPointerEvents && ghostEl) {