{"id":16208482,"url":"https://github.com/ehmicky/is-json-value","last_synced_at":"2025-03-19T08:30:48.608Z","repository":{"id":50600763,"uuid":"519595794","full_name":"ehmicky/is-json-value","owner":"ehmicky","description":"Check if a value is valid JSON.","archived":false,"fork":false,"pushed_at":"2025-03-13T05:04:08.000Z","size":5019,"stargazers_count":6,"open_issues_count":0,"forks_count":0,"subscribers_count":2,"default_branch":"main","last_synced_at":"2025-03-13T06:19:08.741Z","etag":null,"topics":["bigint","circular","cycle","enumerable","exception-handling","exceptions","getters","javascript","json","library","nodejs","parsing","serialization","symbols","tojson","types","typescript","valid","validate","validation"],"latest_commit_sha":null,"homepage":"","language":"JavaScript","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/ehmicky.png","metadata":{"files":{"readme":"README.md","changelog":"CHANGELOG.md","contributing":"CONTRIBUTING.md","funding":null,"license":"LICENSE","code_of_conduct":"CODE_OF_CONDUCT.md","threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2022-07-30T18:47:12.000Z","updated_at":"2025-03-13T05:04:12.000Z","dependencies_parsed_at":"2023-09-21T21:38:30.180Z","dependency_job_id":"82be39c7-0b43-47b3-ad3c-3226a89e8d9a","html_url":"https://github.com/ehmicky/is-json-value","commit_stats":{"total_commits":211,"total_committers":3,"mean_commits":70.33333333333333,"dds":0.023696682464455,"last_synced_commit":"c107e6bbf1cf208fc847ea637e246add2f0d8f03"},"previous_names":[],"tags_count":11,"template":false,"template_full_name":"ehmicky/template-javascript","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ehmicky%2Fis-json-value","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ehmicky%2Fis-json-value/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ehmicky%2Fis-json-value/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/ehmicky%2Fis-json-value/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/ehmicky","download_url":"https://codeload.github.com/ehmicky/is-json-value/tar.gz/refs/heads/main","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":243976471,"owners_count":20377691,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["bigint","circular","cycle","enumerable","exception-handling","exceptions","getters","javascript","json","library","nodejs","parsing","serialization","symbols","tojson","types","typescript","valid","validate","validation"],"created_at":"2024-10-10T10:17:13.649Z","updated_at":"2025-03-19T08:30:48.038Z","avatar_url":"https://github.com/ehmicky.png","language":"JavaScript","funding_links":[],"categories":[],"sub_categories":[],"readme":"[![Node](https://img.shields.io/badge/-Node.js-808080?logo=node.js\u0026colorA=404040\u0026logoColor=66cc33)](https://www.npmjs.com/package/is-json-value)\n[![Browsers](https://img.shields.io/badge/-Browsers-808080?logo=firefox\u0026colorA=404040)](https://unpkg.com/is-json-value?module)\n[![TypeScript](https://img.shields.io/badge/-Typed-808080?logo=typescript\u0026colorA=404040\u0026logoColor=0096ff)](/src/main.d.ts)\n[![Codecov](https://img.shields.io/badge/-Tested%20100%25-808080?logo=codecov\u0026colorA=404040)](https://codecov.io/gh/ehmicky/is-json-value)\n[![Minified size](https://img.shields.io/bundlephobia/minzip/is-json-value?label\u0026colorA=404040\u0026colorB=808080\u0026logo=webpack)](https://bundlephobia.com/package/is-json-value)\n[![Mastodon](https://img.shields.io/badge/-Mastodon-808080.svg?logo=mastodon\u0026colorA=404040\u0026logoColor=9590F9)](https://fosstodon.org/@ehmicky)\n[![Medium](https://img.shields.io/badge/-Medium-808080.svg?logo=medium\u0026colorA=404040)](https://medium.com/@ehmicky)\n\nCheck if a value is valid JSON.\n\n# Hire me\n\nPlease\n[reach out](https://www.linkedin.com/feed/update/urn:li:activity:7117265228068716545/)\nif you're looking for a Node.js API or CLI engineer (11 years of experience).\nMost recently I have been [Netlify Build](https://github.com/netlify/build)'s\nand [Netlify Plugins](https://www.netlify.com/products/build/plugins/)'\ntechnical lead for 2.5 years. I am available for full-time remote positions.\n\n# Features\n\n- Detects [many types](#warnings) of invalid values with JSON\n- Returns [warning messages](#message) to throw or log\n- Returns invalid properties' [path](#path) and [value](#value)\n\n# Example\n\n\u003c!-- eslint-disable symbol-description, fp/no-mutation --\u003e\n\n```js\nimport isJsonValue from 'is-json-value'\n\nconst input = { one: true, two: { three: Symbol() } }\ninput.self = input\n\n// Throws due to cycle with 'self'.\n// Also, 'two.three' would be omitted since it has an invalid JSON type.\nJSON.stringify(input)\n\nconst warnings = isJsonValue(input)\nconst isValidJson = warnings.length === 0 // false\nconsole.log(warnings)\n// [\n//   {\n//     message: 'Property \"two.three\" must not be a symbol.',\n//     path: ['two', 'three'],\n//     value: Symbol(),\n//     reason: 'ignoredSymbolValue'\n//   },\n//   {\n//     message: 'Property \"self\" must not be a circular value.',\n//     path: ['self'],\n//     value: \u003cref *1\u003e { one: true, two: [Object], self: [Circular *1] },\n//     reason: 'unsafeCycle'\n//   }\n// ]\n\nif (!isValidJson) {\n  // Error: Property \"two.three\" must not be a symbol.\n  throw new Error(warnings[0].message)\n}\n```\n\n# Install\n\n```bash\nnpm install is-json-value\n```\n\nThis package works in both Node.js \u003e=18.18.0 and\n[browsers](https://raw.githubusercontent.com/ehmicky/dev-tasks/main/src/browserslist).\n\nThis is an ES module. It must be loaded using\n[an `import` or `import()` statement](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c),\nnot `require()`. If TypeScript is used, it must be configured to\n[output ES modules](https://www.typescriptlang.org/docs/handbook/esm-node.html),\nnot CommonJS.\n\n# API\n\n## isJsonValue(input)\n\n`input` `any`\\\n_Return value_: [`Warning[]`](#warning)\n\nReturns an array of [warnings](#warning). If `input` is valid to serialize as\nJSON, that array is empty.\n\n### Warning\n\nEach warning is an object indicating that a specific property is invalid to\nserialize as JSON. The same property might have multiple warnings.\n\n#### message\n\n_Type_: `string`\n\nWarning message, like `'Property \"example\" must not be a symbol.'`\n\n#### path\n\n_Type_: `Array\u003cstring | symbol | number\u003e`\n\nPath to the invalid property. Empty array if this is the top-level value.\n\n#### value\n\n_Type_: `unknown`\n\nValue of the invalid property.\n\n#### reason\n\n_Type_: `string`\n\nReason for the warning among:\n\n- [Invalid type](#invalid-types): [`\"ignoredFunction\"`](#functions),\n  [`\"ignoredUndefined\"`](#undefined), [`\"ignoredSymbolValue\"`](#symbol-values),\n  [`\"ignoredSymbolKey\"`](#symbol-keys),\n  [`\"unstableInfinite\"`](#nan-and-infinity), [`\"unresolvedClass\"`](#classes),\n  [`\"ignoredNotEnumerable\"`](#non-enumerable-keys),\n  [`\"ignoredArrayProperty\"`](#array-properties)\n- [Throws an exception](#exceptions): [`\"unsafeCycle\"`](#cycles),\n  [`\"unsafeBigInt\"`](#bigint), [`\"unsafeSize\"`](#big-properties),\n  [`\"unsafeException\"`](#infinite-recursion),\n  [`\"unsafeToJSON\"`](#exceptions-in-tojson),\n  [`\"unsafeGetter\"`](#exceptions-in-getters)\n\n# Warnings\n\nThis is the list of possible warnings.\n\n## Invalid types\n\nJSON only supports booleans, numbers, strings, arrays, objects and `null`. Any\nother type is omitted or transformed by `JSON.stringify()`.\n\n### Functions\n\n```js\nconst invalidJson = { prop: () =\u003e {} }\nJSON.stringify(invalidJson) // '{}'\n```\n\n### Undefined\n\n```js\nconst invalidJson = { prop: undefined }\nJSON.stringify(invalidJson) // '{}'\n```\n\n### Symbol values\n\n\u003c!-- eslint-disable symbol-description --\u003e\n\n```js\nconst invalidJson = { prop: Symbol() }\nJSON.stringify(invalidJson) // '{}'\n```\n\n### Symbol keys\n\n\u003c!-- eslint-disable symbol-description --\u003e\n\n```js\nconst invalidJson = { [Symbol()]: true }\nJSON.stringify(invalidJson) // '{}'\n```\n\n### NaN and Infinity\n\n```js\nconst invalidJson = { one: Number.NaN, two: Number.POSITIVE_INFINITY }\nJSON.stringify(invalidJson) // '{\"one\":null,\"two\":null}'\n```\n\n### Classes\n\n```js\nconst invalidJson = { prop: new Set([]) }\nJSON.stringify(invalidJson) // '{\"prop\":{}}'\n```\n\n### Non-enumerable keys\n\n\u003c!-- eslint-disable fp/no-mutating-methods --\u003e\n\n```js\nconst invalidJson = {}\nObject.defineProperty(invalidJson, 'prop', { value: true, enumerable: false })\nJSON.stringify(invalidJson) // '{}'\n```\n\n### Array properties\n\n\u003c!-- eslint-disable fp/no-mutation --\u003e\n\n```js\nconst invalidJson = []\ninvalidJson.prop = true\nJSON.stringify(invalidJson) // '[]'\n```\n\n## Exceptions\n\n`JSON.stringify()` can throw on specific properties.\n\n### Cycles\n\n\u003c!-- eslint-disable fp/no-mutation --\u003e\n\n```js\nconst invalidJson = { prop: true }\ninvalidJson.self = invalidJson\nJSON.stringify(invalidJson) // Throws: Converting circular structure to JSON\n```\n\n### BigInt\n\n```js\nconst invalidJson = { prop: 0n }\nJSON.stringify(invalidJson) // Throws: Do not know how to serialize a BigInt\n```\n\n### Big properties\n\n```js\nconst invalidJson = { prop: '\\n'.repeat(5e8) }\nJSON.stringify(invalidJson) // Throws: Invalid string length\n```\n\n### Infinite recursion\n\n```js\nconst invalidJson = { toJSON: () =\u003e ({ invalidJson }) }\nJSON.stringify(invalidJson) // Throws: Maximum call stack size exceeded\n```\n\n### Exceptions in `toJSON()`\n\n```js\nconst invalidJson = {\n  prop: {\n    toJSON: () =\u003e {\n      throw new Error('example')\n    },\n  },\n}\nJSON.stringify(invalidJson) // Throws: example\n```\n\n### Exceptions in getters\n\n\u003c!-- eslint-disable fp/no-get-set --\u003e\n\n```js\nconst invalidJson = {\n  get prop() {\n    throw new Error('example')\n  },\n}\nJSON.stringify(invalidJson) // Throws: example\n```\n\n### Exceptions in proxies\n\n\u003c!-- eslint-disable fp/no-proxy --\u003e\n\n```js\nconst invalidJson = new Proxy(\n  { prop: true },\n  {\n    get: () =\u003e {\n      throw new Error('example')\n    },\n  },\n)\nJSON.stringify(invalidJson) // Throws: example\n```\n\n# Related projects\n\n- [`safe-json-value`](https://github.com/ehmicky/safe-json-value): ⛑️ JSON\n  serialization should never fail\n- [`truncate-json`](https://github.com/ehmicky/truncate-json): Truncate a JSON\n  string\n- [`guess-json-indent`](https://github.com/ehmicky/guess-json-indent): Guess the\n  indentation of a JSON string\n\n# Support\n\nFor any question, _don't hesitate_ to [submit an issue on GitHub](../../issues).\n\nEveryone is welcome regardless of personal background. We enforce a\n[Code of conduct](CODE_OF_CONDUCT.md) in order to promote a positive and\ninclusive environment.\n\n# Contributing\n\nThis project was made with ❤️. The simplest way to give back is by starring and\nsharing it online.\n\nIf the documentation is unclear or has a typo, please click on the page's `Edit`\nbutton (pencil icon) and suggest a correction.\n\nIf you would like to help us fix a bug or add a new feature, please check our\n[guidelines](CONTRIBUTING.md). Pull requests are welcome!\n\n\u003c!-- Thanks go to our wonderful contributors: --\u003e\n\n\u003c!-- ALL-CONTRIBUTORS-LIST:START --\u003e\n\u003c!-- prettier-ignore --\u003e\n\u003c!--\n\u003ctable\u003e\u003ctr\u003e\u003ctd align=\"center\"\u003e\u003ca href=\"https://fosstodon.org/@ehmicky\"\u003e\u003cimg src=\"https://avatars2.githubusercontent.com/u/8136211?v=4\" width=\"100px;\" alt=\"ehmicky\"/\u003e\u003cbr /\u003e\u003csub\u003e\u003cb\u003eehmicky\u003c/b\u003e\u003c/sub\u003e\u003c/a\u003e\u003cbr /\u003e\u003ca href=\"https://github.com/ehmicky/is-json-value/commits?author=ehmicky\" title=\"Code\"\u003e💻\u003c/a\u003e \u003ca href=\"#design-ehmicky\" title=\"Design\"\u003e🎨\u003c/a\u003e \u003ca href=\"#ideas-ehmicky\" title=\"Ideas, Planning, \u0026 Feedback\"\u003e🤔\u003c/a\u003e \u003ca href=\"https://github.com/ehmicky/is-json-value/commits?author=ehmicky\" title=\"Documentation\"\u003e📖\u003c/a\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/table\u003e\n --\u003e\n\u003c!-- ALL-CONTRIBUTORS-LIST:END --\u003e\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fehmicky%2Fis-json-value","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fehmicky%2Fis-json-value","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fehmicky%2Fis-json-value/lists"}