Create nest

snippets/nest

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+### nest
+
+Given a flat array of objects linked to one another, it will nest them recursively.
+Useful for nesting comments, such as the ones on reddit.com.
+
+Use recursion. Use `Array.filter()` to filter the items where the `id` matches the `link`,
+then use `Array.map()` to map each one to a new object that has a `children` property which
+recursively nests the items based on which ones are children of the current item.
+
+```js
+const nest = (items, id = null, link = 'parent_id') =>
+  items.filter(item => item[link] === id).map(item => ({ ...item, children: nest(items, item.id) }))
+```
+
+```js
+// One top level comment
+const comments = [
+  { id: 1, parent_id: null },
+  { id: 2, parent_id: 1 },
+  { id: 3, parent_id: 1 },
+  { id: 4, parent_id: 2 },
+  { id: 5, parent_id: 4 }
+]
+const nestedComments = nest(comments) // [{ id: 1, parent_id: null, children: [...] }]
+```
+