By default, when you modify the value of an `each` block, it will add and remove items at the *end* of the block, and update any values that have changed. That might not be what you want.
It's easier to show why than to explain. Click the 'Remove first thing' button a few times, and notice what happens: It removes the first `<Thing>` component, but the *last* DOM node. Then it updates the `name` value in the remaining DOM nodes, but not the emoji.
> You can use any object as the key, as Svelte uses a `Map` internally — in other words you could do `(thing)` instead of `(thing.id)`. Using a string or number is generally safer, however, since it means identity persists without referential equality, for example when updating with fresh data from an API server.