jsonize.vim

Pretty-print and structure almost-JSON so it looks like JSON — no jq, and no value changes.

This plugin was born from the need to quickly inspect debug output that isn’t valid JSON. Single-line, unquoted, or partially structured data that jq can’t parse while keeping the original values visible.

This plugin is intentionally conservative: it quotes keys and single-quoted strings, fixes commas/newlines/indentation, and removes trailing commas — but it does not normalize values like NaN, Infinity, undefined, or placeholders such as [Object] / [Array]. Those are preserved verbatim.

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What It Does (Structure-only)

• Quotes unquoted object keys → "key": value
• Converts 'single-quoted strings' → "double-quoted strings"
• Adds consistent newlines and indentation
• Removes trailing commas before ] or }
• Tidies up extra spaces/line breaks

What it does not do:

• ❌ No parsing or validation (output may not be valid JSON)
• ❌ No value normalization (keeps NaN, Infinity, undefined, [Object], [Array], etc.)
• ❌ No type coercion or schema checks

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Requirements

• Vim 8+ or Neovim
• No external tools required

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Installation

vim-plug

Plug 'leonskim/jsonize.vim'

Vundle

Plugin 'leonskim/jsonize.vim'

packer.nvim

use 'leonskim/jsonize.vim'

Restart Vim/Neovim and run :helptags ALL if needed.

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Key Mappings

• Visual mode → <leader>jf formats the selected text
• Normal mode → <leader>jf runs :Jsonize (defaults to whole buffer)

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Commands

• :Jsonize — Format entire buffer
• :[range]Jsonize — Format only the given range

Examples

:Jsonize
:42Jsonize
:3,15Jsonize
:'<,'>Jsonize
:%Jsonize

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Examples (Structure preserved, values unchanged)

Input

{ user: 'alice', plan: Pro, lastLogin: NaN, meta: [Object] }

Output

{
  "user": "alice",
  "plan": Pro,
  "lastLogin": NaN,
  "meta": [Object]
}

Input

[
  {id:1, name:'A', extra:[Array], price:Infinity},
  {id:2, name:'B', extra:[Object], price:undefined},
]

Output

[
  {
    "id": 1,
    "name": "A",
    "extra": [Array],
    "price": Infinity
  },
  {
    "id": 2,
    "name": "B",
    "extra": [Object],
    "price": undefined
  }
]

Note: Trailing commas are removed, keys/strings are quoted, spacing/indentation are normalized. Values like Infinity, NaN, undefined, [Object], [Array] are left as-is.

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Caveats

• The result looks like JSON but may not be valid JSON because special tokens are preserved.
• If you need strict JSON, run a real normalizer/serializer after inspection (e.g., convert NaN/Infinity/undefined to null in your pipeline).

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License

MIT License — © Leon Kim