Registry / serialization / tv4

tv4

JSON →
library1.3.0jsnpmunverified

tv4 is an abandoned JavaScript library designed for validating data against JSON Schema Draft v4 exclusively. Its latest release, version 1.3.0, was published in August 2015, with no subsequent updates or active maintenance. The library differentiates itself by offering synchronous, single-error validation by default, with optional methods for collecting multiple errors (`validateMultiple`) or a structured result object (`validateResult`) to better support multi-threaded environments where global state (`tv4.error`, `tv4.missing`) is problematic. It also supports `$ref` for referencing external schemas and has an optional mechanism for handling cyclical JavaScript objects. Due to its strict adherence to Draft v4 and lack of updates, it does not support newer JSON Schema drafts (like Draft 6, 7, 2019-09, or 2020-12) and is not recommended for new projects requiring modern schema features or active support.

serialization
npm install tv4
github ↗package ↗
INSTALL
IMPORT
SIG · TV4
T
tv4
serializationjavascriptv1.3.0
Install
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Import
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Disk
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Pass rate
0/ 6
Env Coverage0 / 6
glibc
18–22
musl
18–22
Install & Compatibility
Where this runs
tested against v? · npm install
Install × environment matrix
Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux
musl
node 18–226 runs
build_error
glibc
node 18–226 runs
build_error
Code
Verified usage

Verified import paths — ran on the pinned version, not inferred.

tv4
✓ const tv4 = require('tv4');
✗ import tv4 from 'tv4';
tv4 is primarily a CommonJS module. While bundlers might process ESM imports, direct ESM import syntax without specific configuration or interop is not natively supported for older Node.js versions or direct browser use.
validate
✓ const tv4 = require('tv4'); const isValid = tv4.validate(data, schema);
✗ import { validate } from 'tv4'; const isValid = validate(data, schema);
The core validation functions are properties of the default exported `tv4` object, not named exports. Access them via the `tv4` object.
tv4.addSchema
✓ const tv4 = require('tv4'); tv4.addSchema(url, schema);
✗ import { addSchema } from 'tv4';
Utility functions like `addSchema` are also methods of the global `tv4` object.

This quickstart demonstrates basic synchronous JSON Schema Draft v4 validation, including how to handle validation results and errors, disallow additional properties, and use the `validateResult` method for safer error handling in shared environments.

const tv4 = require('tv4'); // Define your data to be validated const data = { name: 'John Doe', age: 30, email: 'john.doe@example.com', occupation: 'Software Engineer' }; // Define your JSON Schema Draft v4 const schema = { "$schema": "http://json-schema.org/draft-04/schema#", "type": "object", "properties": { "name": { "type": "string", "minLength": 1 }, "age": { "type": "integer", "minimum": 0 }, "email": { "type": "string", "format": "email" } }, "required": ["name", "age", "email"], "additionalProperties": false // Disallow unknown properties }; // Perform validation const result = tv4.validateResult(data, schema, true); // Use validateResult for structured output and checkRecursive if (!result.valid) { console.error('Validation failed!'); console.error('Error:', result.error); if (result.missing && result.missing.length > 0) { console.warn('Missing schemas:', result.missing); } } else { console.log('Validation successful!'); } // Example with an invalid data const invalidData = { name: 'Jane Doe', age: 'twenty', email: 'invalid-email' }; const invalidResult = tv4.validateResult(invalidData, schema); if (!invalidResult.valid) { console.error('\nValidation failed for invalid data:'); console.error('Error:', invalidResult.error); }
Debug
Known issues
breakingtv4 is no longer actively maintained. Its last release was in 2015, and it strictly supports only JSON Schema Draft v4. It does not support newer drafts (like Draft 6, 7, 2019-09, or 2020-12), meaning schemas written for modern JSON Schema specifications will not validate correctly.
fix
For new projects or projects requiring modern JSON Schema features, consider using actively maintained alternatives like Ajv (Another JSON Schema Validator) which supports all current drafts and offers better performance and extensibility.
affects: >=1.0.0
gotchaThe default `tv4.validate` method returns a boolean and stores the last validation error in `tv4.error` and missing schemas in `tv4.missing`. These are global properties, making `tv4.validate` unsafe for concurrent or multi-threaded environments, as validation results can be overwritten.
fix
Always use `tv4.validateResult(data, schema)` or `tv4.validateMultiple(data, schema)` for safer, self-contained result objects that include `valid`, `error` (or `errors`), and `missing` properties, ensuring thread-safety and consistent error reporting.
affects: >=1.0.0
gotchaBy default, `tv4` stops validation on the first encountered error. This means `tv4.validate` and `tv4.validateResult` will only report one error at a time.
fix
To collect all validation errors, use `tv4.validateMultiple(data, schema)`. This method returns an object containing an `errors` array with all detected issues.
affects: >=1.0.0
gotchaValidation of cyclical JavaScript objects (objects that reference themselves, which are not valid JSON but can exist in JavaScript) can lead to 'too much recursion' errors or script hangs.
fix
When validating objects that might contain circular references, pass `true` as the third argument to any validation method (e.g., `tv4.validate(data, schema, true)`). This enables recursive checking, preventing infinite loops.
affects: >=1.0.0
gotchaBy default, `tv4` ignores properties in your data that are not defined in the schema. This can lead to unexpected behavior if you intend for unknown properties to cause validation failure.
fix
To treat unknown properties as validation errors, set the `banUnknownProperties` flag to `true` on the `tv4` object (e.g., `tv4.banUnknownProperties = true;`). Alternatively, set `"additionalProperties": false` in your schema.
affects: >=1.0.0
gotchaAsynchronous validation, which allows `tv4` to fetch missing schemas dynamically, is not built-in and requires an external file (`tv4.async-jquery.js`) that currently has a dependency on jQuery.
fix
If asynchronous schema fetching is required, include `tv4.async-jquery.js`. For environments without jQuery, the README suggests the code is simple enough to adapt, but no official alternatives are provided. Consider pre-loading all schemas via `tv4.addSchema` if possible to avoid this dependency.
affects: >=1.0.0
Errors
Common errors & fixes
RangeError: Maximum call stack size exceeded
Attempting to validate a JavaScript object with circular references without enabling recursive checking.
fix
Pass `true` as the third argument to the validation method: `tv4.validate(data, schema, true);` or `tv4.validateResult(data, schema, true);`.
{ valid: false, error: { ... }, missing: [] } where error seems incorrect or refers to a previous validation.
Using `tv4.validate(data, schema)` in an environment where multiple validations might occur concurrently, leading to the global `tv4.error` property being overwritten.
fix
Switch to `tv4.validateResult(data, schema)` which returns a self-contained result object, preventing global state conflicts.
Validation passes (returns `true`) but some schemas referenced by `$ref` are not actually validated.
The referenced schemas were not added to `tv4` using `tv4.addSchema(url, schema)`, and the validation was synchronous. `tv4.missing` will indicate which schemas were not found.
fix
Ensure all referenced schemas are pre-loaded using `tv4.addSchema(url, schema)` before validation. Alternatively, if asynchronous fetching is set up, ensure it's properly configured and awaited.
JSON data contains an extra field not defined in the schema, but validation still passes.
By default, `tv4` ignores properties not explicitly defined in the schema.
fix
Set `tv4.banUnknownProperties = true;` globally or add `"additionalProperties": false` to your schema to disallow undeclared properties.
Upgrade
Version history
1.3.0latest on npm
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Dependencies

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Agent activity
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Resources
githubhttps://github.com/geraintluff/tv4 ↗
packagehttps://www.npmjs.com/package/tv4 ↗