{{#each things as thing}}
	{{#if visible}}
		<div in:foo out:bar>{{thing}}</div>
	{{/if}}
{{/each}}

<script>
	export default {
		transitions: {
			foo: function ( node, params ) {
				return {
					duration: 100,
					tick: t => {
						node.foo = t;
					}
				};
			},

			bar: function ( node, params ) {
				return {
					duration: 100,
					tick: t => {
						node.bar = t;
					}
				};
			}
		}
	};
</script>