30 lines
1.1 KiB
Markdown
30 lines
1.1 KiB
Markdown
### nest
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Given a flat array of objects linked to one another, it will nest them recursively.
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Useful for nesting comments, such as the ones on reddit.com.
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Use recursion. Use `Array.filter()` to filter the items where the `id` matches the `link`,
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then use `Array.map()` to map each one to a new object that has a `children` property which
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recursively nests the items based on which ones are children of the current item. Omit the second
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argument, `id`, to default to `null` which indicates the object is not linked to another one (i.e.,
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it is a top level). Omit the third argument, `link`, to use `'parent_id'` as the default property
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which links the object to another one by its `id`.
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```js
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const nest = (items, id = null, link = 'parent_id') =>
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items.filter(item => item[link] === id).map(item => ({ ...item, children: nest(items, item.id) }))
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```
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```js
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// One top level comment
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const comments = [
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{ id: 1, parent_id: null },
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{ id: 2, parent_id: 1 },
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{ id: 3, parent_id: 1 },
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{ id: 4, parent_id: 2 },
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{ id: 5, parent_id: 4 }
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]
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const nestedComments = nest(comments) // [{ id: 1, parent_id: null, children: [...] }]
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```
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