---
title: How to read Bun.lockb in Neovim
date: 2024-09-29
isPublished: true
lang: 'en'
---

> [日本語版](/blog/2023-09-27-zenn-c097917f163431-ja)

> [!NOTE]
> Edit(29, Jan, 2025):
> Bun introduced [text-based lockfile](https://bun.sh/docs/install/lockfile#text-based-lockfile) which is readable on Neovim.

[**Bun**](https://bun.sh/) is a really nice JavaScript tool! I really love it.

One of the coolest things in Bun is the aspect of package manager. `bun install` is extremely fast. Bun uses a unique lockfile called `Bun.lockb`. This is similar to `package-lock.json` in `npm`. This binary lockfile speeds up the installation process.

However, due to its binary format, you cannot view the content of `Bun.lockb` directly.
This is somewhat inconvenient.

![bun.lockb is a binary](./bun-lockfile.png '`bun.lockb` is a binary file so you cannot see anything orz')

## For VSCode Users

You can simply install [the official extension](https://marketplace.visualstudio.com/items?itemName=oven.bun-vscode) and it works.

## For Vim/Neovim Users

There is no official plugin for Vim/Neovim. Let's make it by ourselves!

In fact, bun has outputs `Bun.lock` in yarn v1 format by:

```sh
bun bun.lockb
```

So, we can utilise this feature!

Let's write a simple vim plugin that automatically runs `bun bun.lockb` when you open a `Bun.lockb` file.

### Lua Version

If you are using Neovim, you can write in Lua:

```lua
vim.api.nvim_create_autocmd("BufReadCmd", {
    pattern = "bun.lockb",
    callback = function(ev)
        -- get the absolute path of the current file
        local path = vim.fn.expand("%:p")
        -- run command 'bun ' .. path and get stdout
        local output = vim.fn.systemlist("bun " .. path)
        -- set output to current buffer
        vim.api.nvim_buf_set_lines(0, 0, -1, true, output)
        -- set filetype to yarn.lock
        vim.opt_local.filetype = "conf"
        -- set readonly
        vim.opt_local.readonly = true
        -- set nomodifiable
        vim.opt_local.modifiable = false
    end,
})
```

### Vim Script Version

Also, Vim Script is great because both Vim and Neovim can use it!

```vimscript
augroup BunLockb
    autocmd!
    autocmd BufReadCmd bun.lockb
        \ let path = expand("%:p") |
        \ let output = systemlist("bun " . path) |
        \ call setline(1, output) |
        \ setlocal filetype=conf |
        \ setlocal readonly |
        \ setlocal nomodifiable
augroup END
```

![You can view Bun.lockb in Neovim](./bun-lockfile-nvim.avif 'Now you can see `Bun.lockb` in Neovim! Tada!')

I've made [a plugin](https://github.com/ryoppippi/vim-bun-lock) based on this article, so you can just install it in your way!

**Enjoy!**