diff --git a/snippets/nest.md b/snippets/nest.md new file mode 100644 index 000000000..40eb911c7 --- /dev/null +++ b/snippets/nest.md @@ -0,0 +1,29 @@ +### 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. Omit the second +argument, `id`, to default to `null` which indicates the object is not linked to another one (i.e., +it is a top level). Omit the third argument, `link`, to use `'parent_id'` as the default property +which links the object to another one by its `id`. + +```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: [...] }] +``` + diff --git a/tag_database b/tag_database index 54db11193..8d8f55279 100644 --- a/tag_database +++ b/tag_database @@ -162,6 +162,7 @@ minBy:math,array,function minN:array,math mostPerformant:utility,function negate:function +nest:object none:array,function nthArg:utility,function nthElement:array