---
title: "Repeat content inside one file"
description: "Emit one block of content per array item inside a single file, with List."
source: "https://jostraca.org/how-to/repeat-content-in-one-file/"
---

# Repeat content inside one file

Emit one block of content per array item inside a single file, with List.

Rendered from [`docs/how-to/repeat-content-in-one-file.md`](https://github.com/jostraca/jostraca/blob/master/docs/how-to/repeat-content-in-one-file.md) in the generator repository — where a correction belongs, and where the test suite runs every example on this page or states why it does not.

When the repetition is _inside_ a file rather than across files, `List` emits one block per item.

```js
import { Jostraca, Project, File, Content, List } from 'jostraca'

const users = [
  { name: 'Alice', role: 'admin' },
  { name: 'Bob', role: 'user' },
]

await Jostraca().generate({ folder: './out' }, () => {
  Project({}, () => {
    File({ name: 'users.txt' }, () => {

      List({ item: users, line: false }, ({ replace }) => {
        Content({ src: '{item.name}: {item.role}\n', replace })
      })
    })
  })
})
```

The generated `users.txt`:

```text
Alice: admin
Bob: user
```

Two things in that call are easy to get wrong, and both fail silently.

**`replace` must be threaded through the props form.** The `{item.…}` substitution arrives in the `replace` object the child is handed, and `Content`’s second positional argument is _children_, not props. So `Content('{item.name}', {replace})` substitutes nothing and writes the marker text verbatim. Use `Content({src: …, replace})`.

**`line: false` turns off the trailing newline.** By default `List` emits one after the whole list, and only the exact value `false` disables it—`line: 0` still emits.

`{item.path}` resolves with the same path grammar as `getx`, so `{item.a.b}` works. It cannot address a `$`\-suffixed key, though, so `{item.val$}`, `{item.key$}` and `{item.index$}` all come out empty. For a list of scalars, or when you want the index, use the `item` argument directly:

```js
import { Jostraca, Project, File, Content, List } from 'jostraca'

await Jostraca().generate({ folder: './out' }, () => {
  Project({}, () => {
    File({ name: 'flags.txt' }, () => {
      List({ item: ['alpha', 'beta'], line: false }, ({ item }) => {
        Content('--' + item.val$ + '=' + item.index$ + '\n')
      })
    })
  })
})
```

The generated `flags.txt`:

```text
--alpha=0
--beta=1
```

An unresolved `{item.nope}` yields the empty string, unlike `$$nope$$`, which is left in place. That asymmetry is a trap when a property name changes: the marker vanishes rather than shouting.

## See also

-   [Branch and loop in a generator](https://jostraca.org/how-to/branch-and-loop) when the repetition spans files.
-   [Component reference](https://jostraca.org/docs/reference-components#list).