JSON / JSONL Preview
English | 简体中文
Examples
English
A safe, paged VS Code preview for JSON, JSONL and NDJSON. It provides a lazy JSON tree, line-isolated JSONL diagnostics, filtering, stable sorting, locale-aware date display, JMESPath projection, source navigation, formatting, high-confidence repair previews, export, and format conversion.
Use JSON(L) Preview: Open Preview or Open With.... Clean local JSONL and NDJSON files above the configured threshold use the read-only streaming provider, so the extension host and webview never receive the complete file. JSON files, non-file URIs, and documents with unsaved changes use normal mode and are subject to its size limit.
Select JSON or JSON Lines content in any text editor, then right-click and choose JSON(L) Preview: Preview Selection to open it in a temporary preview document.
Enter a plain value to search JSON scalar values; in JSONL previews this filters the table to matching records. JMESPath expressions such as users[?active].name remain available for projections and structured record filtering. Right-click a node to copy data or a directly reusable JMESPath-compatible JSONPath; JSONL row details support the same actions.
String scalar values provide inline actions to view their full content, copy them, or open them in a temporary tab. Hold Alt/Option while opening content to reuse the current tab instead. The full-content viewer supports Ctrl/Cmd+F search and context-menu actions for selected text.
The preview does not execute workspace code or upload file content. Source changes are applied through VS Code edits and remain undoable.
Settings
Settings are read when a preview opens. Reopen an existing preview after changing them.
| Setting |
Default |
Range / values |
Effect |
jsonlPreview.showEditorTitleIcon |
true |
Boolean |
Shows the preview action in the editor title bar. |
jsonlPreview.json.indent |
2 |
1–8 |
Spaces used by Format Document. |
jsonlPreview.json.allowComments |
false |
Boolean |
Allows comments in JSON previews only. |
jsonlPreview.json.allowTrailingComma |
false |
Boolean |
Allows trailing commas in JSON previews only. |
jsonlPreview.json.maxAutoExpandDepth |
10 |
1–100 |
Automatically expands the JSON tree through this level; deeper nodes can still be opened manually. |
jsonlPreview.jsonl.pageSize |
1000 |
20–1000 |
Records requested per JSONL/NDJSON page. |
jsonlPreview.jsonl.schemaSampleSize |
1000 |
10–10000 |
Initial records sampled to discover table columns. Fields that occur only later may not appear as columns. |
jsonlPreview.jsonl.ignoreEmptyLines |
true |
Boolean |
Ignores blank physical lines; when disabled, they appear as error rows. |
jsonlPreview.largeFileThresholdMB |
50 |
At least 1 |
Switches clean local JSONL/NDJSON files above the threshold to read-only streaming mode. It does not apply to JSON. |
jsonlPreview.normalModeMaxFileMB |
100 |
1–1024 |
Maximum complete-file load in normal mode; also bounds conversion and non-file export. |
jsonlPreview.maxLineLengthMB |
5 |
0.1–1024 |
Maximum JSONL/NDJSON line parsed completely; longer lines become error rows with a truncated preview. |
jsonlPreview.maxSortableRows |
1000000 |
1000–100000000 |
Maximum indexed physical-line count for field sorting. Original-order sorting still works. |
jsonlPreview.queryCacheMB |
128 |
8–4096 |
Memory budget for the line index, query results, and sorting data. A broad query can exceed this budget. |
jsonlPreview.timezone |
system |
system or IANA time zone |
Displays recognized timestamps in this zone, for example Asia/Shanghai. Invalid zones leave the original value unchanged. |
Keep largeFileThresholdMB at or below normalModeMaxFileMB. Otherwise, a JSONL/NDJSON file between the two limits cannot enter streaming mode and is too large for normal mode. Large-file mode requires an unchanged local file and is read-only; opening its source explicitly loads the complete file into VS Code.
简体中文
一款安全、支持分页浏览的 VS Code JSON、JSONL 和 NDJSON 文件预览插件。它提供按需加载的 JSON 树、逐行隔离的 JSONL 错误诊断、筛选、稳定排序、适配界面语言的日期显示、JMESPath 投影、源码定位、格式化、高置信度修复预览、导出和格式转换等功能。
使用 JSON(L) Preview: Open Preview 命令或 打开方式...（Open With...） 即可打开预览。没有未保存修改的本地 JSONL 和 NDJSON 文件超过配置阈值后会使用只读流式读取，因此扩展宿主和 Webview 都不会接收完整文件内容。JSON 文件、非本地文件 URI 和包含未保存修改的文档使用普通模式，并受普通模式大小上限约束。
在任意文本编辑器中选中 JSON 或 JSON Lines 内容，右键选择 JSON(L) 预览: 预览所选内容，即可通过临时文档打开预览。
输入普通文本可以搜索 JSON 中的标量值；在 JSONL 预览中，则会筛选出匹配的记录。也可以使用 users[?active].name 等 JMESPath 表达式进行投影和结构化记录筛选。右键单击节点，可以复制数据或可直接复用、兼容 JMESPath 的 JSONPath；JSONL 行详情也支持相同操作。
字符串标量值提供行内操作，可查看完整内容、复制，或在临时标签页中打开。打开内容时按住 Alt/Option，则会改为复用当前标签页。完整内容查看器支持使用 Ctrl/Cmd+F 搜索，也支持通过右键菜单操作选中的文本。
本插件不会执行工作区代码，也不会上传文件内容。对源文件的修改均通过 VS Code 编辑操作应用，并且可以撤销。
设置项
设置在打开预览时读取。修改后，请重新打开已有预览。
| 设置项 |
默认值 |
范围 / 可选值 |
作用 |
jsonlPreview.showEditorTitleIcon |
true |
布尔值 |
在编辑器标题栏显示预览操作入口。 |
jsonlPreview.json.indent |
2 |
1–8 |
格式化文档 使用的空格数。 |
jsonlPreview.json.allowComments |
false |
布尔值 |
仅允许 JSON 预览包含注释。 |
jsonlPreview.json.allowTrailingComma |
false |
布尔值 |
仅允许 JSON 预览包含尾随逗号。 |
jsonlPreview.json.maxAutoExpandDepth |
10 |
1–100 |
JSON 树自动展开到此层；更深节点仍可手动展开。 |
jsonlPreview.jsonl.pageSize |
1000 |
20–1000 |
每页请求的 JSONL/NDJSON 记录数。 |
jsonlPreview.jsonl.schemaSampleSize |
1000 |
10–10000 |
用于发现表格列的前置记录采样数；仅在更后面出现的字段可能不会成为表格列。 |
jsonlPreview.jsonl.ignoreEmptyLines |
true |
布尔值 |
忽略空白物理行；关闭后，空白行会显示为错误行。 |
jsonlPreview.largeFileThresholdMB |
50 |
不小于 1 |
本地且未修改的 JSONL/NDJSON 超过阈值后切换到只读流式模式；不适用于 JSON。 |
jsonlPreview.normalModeMaxFileMB |
100 |
1–1024 |
普通模式完整加载文件的上限，同时约束格式转换和非本地导出。 |
jsonlPreview.maxLineLengthMB |
5 |
0.1–1024 |
完整解析 JSONL/NDJSON 单行的上限；超长行会成为错误行并仅显示截断预览。 |
jsonlPreview.maxSortableRows |
1000000 |
1000–100000000 |
允许按字段排序的已索引物理行数上限；按原始顺序排序仍可使用。 |
jsonlPreview.queryCacheMB |
128 |
8–4096 |
行索引、查询结果和排序数据的内存预算；宽泛查询可能超出预算。 |
jsonlPreview.timezone |
system |
system 或 IANA 时区 |
使用指定时区显示识别到的时间戳，例如 Asia/Shanghai；无效时区会保留原值。 |
建议让 largeFileThresholdMB 小于或等于 normalModeMaxFileMB。否则，大小介于两者之间的 JSONL/NDJSON 文件既不会进入流式模式，又会超过普通模式上限。大文件模式要求本地文件没有未保存修改，并且只读；显式打开源码会让 VS Code 完整加载文件。
Changelog
Unreleased
0.1.11 — 2026-08-26
- Added locale-aware date formatting for Chinese and English interfaces.
- Hold
Alt while opening content to switch between a temporary preview tab and the current tab.
0.1.10 — 2026-08-26
- Added search to the full-content viewer.
- Added copy and open actions for string scalar values, with clearer temporary-tab hints and improved value layout.
- Simplified scalar-value expansion behavior and expanded the related test coverage.
0.1.9 — 2026-08-24
- Added an option to open JSON and JSONL content in the current tab.
0.1.8 — 2026-08-02
- Prevented the paginator from being clipped and duplicate drawer styles from being injected when reopening a preview.
- Improved grid performance by caching date formatters and memoizing the grid.
0.1.7 — 2026-08-01
- Added a context menu for selected text in the full-content viewer.
0.1.6 — 2026-07-26
- Added a VS Code theme-aware overlay background for loading states.
0.1.5 — 2026-07-26
- Added resizable JSONL columns and persisted column widths.
- Improved fixed table-header theme integration.
- Updated search and filter placeholders with JMESPath examples.
0.1.4 — 2026-07-24
- Included documentation images in the packaged extension.
- Limited source-map generation to watch builds and configured the VSCE GitHub branch.
0.1.3 — 2026-07-24
- Added localized descriptions for extension settings.
- Expanded the settings documentation and clarified large-file mode limits.
0.1.2 — 2026-07-20
- Added temporary-tab previews for JSONL rows and cells.
- Improved context-menu actions, icons, keyboard navigation, and drawer actions.
- Fixed source-file opening behavior.
0.1.1 — 2026-07-20
- Introduced the initial preview UI, selection-preview menu integration, and final extension package identity.
0.1.0 — 2026-07-19
- Initial release with JSON, JSONL, and NDJSON previews.
