validate-value validates values against JSON schemas. 

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validate-value

# [9.2.0](https://github.com/thenativeweb/validate-value/compare/9.1.7...9.2.0) (2022-01-17)

* Improve readme. ([#405](https://github.com/thenativeweb/validate-value/issues/405)) ([98687b8](https://github.com/thenativeweb/validate-value/commit/98687b82c7b8210e8e8255dc2b170b7b306cf469))

## [9.1.7](https://github.com/thenativeweb/validate-value/compare/9.1.6...9.1.7) (2021-12-07)

* Remove non-existent function from documenation. ([#402](https://github.com/thenativeweb/validate-value/issues/402)) ([4bfb4e3](https://github.com/thenativeweb/validate-value/commit/4bfb4e3a4f6a623180645f9f8c56c82c46988052))

## [9.1.6](https://github.com/thenativeweb/validate-value/compare/9.1.5...9.1.6) (2021-08-16)

* bump typedescriptor from 4.0.11 to 4.0.12 ([#382](https://github.com/thenativeweb/validate-value/issues/382)) ([ebfccb3](https://github.com/thenativeweb/validate-value/commit/ebfccb3743a8a775202e390e7fddfcb7fbdf6bf5))

## [9.1.5](https://github.com/thenativeweb/validate-value/compare/9.1.4...9.1.5) (2021-08-16)

* bump ajv-formats from 2.1.0 to 2.1.1 ([#385](https://github.com/thenativeweb/validate-value/issues/385)) ([e09790a](https://github.com/thenativeweb/validate-value/commit/e09790a4aa0a72578a7c07447fa17170d903d062))

## [9.1.4](https://github.com/thenativeweb/validate-value/compare/9.1.3...9.1.4) (2021-08-02)

* bump typedescriptor from 4.0.10 to 4.0.11 ([#377](https://github.com/thenativeweb/validate-value/issues/377)) ([5585327](https://github.com/thenativeweb/validate-value/commit/558532798234430bb3873d5a9ad92ff423ac2719))

## [9.1.3](https://github.com/thenativeweb/validate-value/compare/9.1.2...9.1.3) (2021-07-23)

* Update dependencies. ([#376](https://github.com/thenativeweb/validate-value/issues/376)) ([be60c1a](https://github.com/thenativeweb/validate-value/commit/be60c1af2e5fc02350c495981a8be073c67c972d))

## [9.1.2](https://github.com/thenativeweb/validate-value/compare/9.1.1...9.1.2) (2021-07-21)

* bump typedescriptor from 4.0.9 to 4.0.10 ([#373](https://github.com/thenativeweb/validate-value/issues/373)) ([a656cd6](https://github.com/thenativeweb/validate-value/commit/a656cd64a4ee424a51eaa082baef9b1bbb2ce413))

## [9.1.1](https://github.com/thenativeweb/validate-value/compare/9.1.0...9.1.1) (2021-07-21)

* bump ajv from 8.6.1 to 8.6.2 ([#374](https://github.com/thenativeweb/validate-value/issues/374)) ([14dd0ff](https://github.com/thenativeweb/validate-value/commit/14dd0ffa1a8a7d005fd52d3ad5a39385933af84e))

# [9.1.0](https://github.com/thenativeweb/validate-value/compare/9.0.12...9.1.0) (2021-07-10)

* Bump multiple dependencies. ([#370](https://github.com/thenativeweb/validate-value/issues/370)) ([ac94554](https://github.com/thenativeweb/validate-value/commit/ac94554442eff44506c3ec8f03596c9e00aef4dd))

## [9.0.12](https://github.com/thenativeweb/validate-value/compare/9.0.11...9.0.12) (2021-07-06)

* bump ajv from 8.6.0 to 8.6.1 ([#369](https://github.com/thenativeweb/validate-value/issues/369)) ([64e79e4](https://github.com/thenativeweb/validate-value/commit/64e79e4dc05e7f1c09c849bf135cb087aee6b1c6))

## [9.0.11](https://github.com/thenativeweb/validate-value/compare/9.0.10...9.0.11) (2021-06-29)

* bump typedescriptor from 4.0.7 to 4.0.8 ([#365](https://github.com/thenativeweb/validate-value/issues/365)) ([fe9d508](https://github.com/thenativeweb/validate-value/commit/fe9d508417ffdc03eef2809b1434d95409725fb8))

## [9.0.10](https://github.com/thenativeweb/validate-value/compare/9.0.9...9.0.10) (2021-06-28)

* bump typedescriptor from 4.0.4 to 4.0.7 ([#359](https://github.com/thenativeweb/validate-value/issues/359)) ([a3687a1](https://github.com/thenativeweb/validate-value/commit/a3687a18bed0fd83fbf24ccd8d512d3ad7996a4f))

## [9.0.9](https://github.com/thenativeweb/validate-value/compare/9.0.8...9.0.9) (2021-06-14)

* bump defekt from 7.2.0 to 7.2.3 ([#363](https://github.com/thenativeweb/validate-value/issues/363)) ([d837770](https://github.com/thenativeweb/validate-value/commit/d837770f70eaa0ee0e23b0ee32309ff257663fe0))

## [9.0.8](https://github.com/thenativeweb/validate-value/compare/9.0.7...9.0.8) (2021-06-10)

* bump normalize-url from 6.0.0 to 6.0.1 ([#357](https://github.com/thenativeweb/validate-value/issues/357)) ([71ca5d3](https://github.com/thenativeweb/validate-value/commit/71ca5d344504142bbcb0d6566095160f2dd6c8ca))

## [9.0.7](https://github.com/thenativeweb/validate-value/compare/9.0.6...9.0.7) (2021-06-10)

* bump trim-newlines from 3.0.0 to 3.0.1 ([#358](https://github.com/thenativeweb/validate-value/issues/358)) ([9ce36c5](https://github.com/thenativeweb/validate-value/commit/9ce36c5045d972e4d355f325c72a7227bab15230))

## [9.0.6](https://github.com/thenativeweb/validate-value/compare/9.0.5...9.0.6) (2021-06-07)

  "description": "validate-value validates values against JSON schemas.",

      "email": "golo.roden@thenativeweb.io"

      "email": "jan-hendrik.grundhoefer@thenativeweb.io"

      "email": "hannes.leutloff@thenativeweb.io"

      "email": "alexander.kampf@thenativeweb.io"

    "semantic-release-configuration": "2.0.5"

    "url": "git://github.com/thenativeweb/validate-value.git"

| Category         | Status                                                                                                      |

| ---------------- | ----------------------------------------------------------------------------------------------------------- |

| Version          | [![npm](https://img.shields.io/npm/v/validate-value)](https://www.npmjs.com/package/validate-value)         |

| Dependencies     | ![David](https://img.shields.io/david/thenativeweb/validate-value)                                          |

| Dev dependencies | ![David](https://img.shields.io/david/dev/thenativeweb/validate-value)                                      |

| Build            | ![GitHub Actions](https://github.com/thenativeweb/validate-value/workflows/Release/badge.svg?branch=main) |

| License          | ![GitHub](https://img.shields.io/github/license/thenativeweb/validate-value)                                |

The rewrite of `validate-value` in version 9.0.0 follows the infamous quote "parse, don't validate"<sup>[1](#footnote-1)</sup>. The quote asserts that parsing data is more valuable than validating it. This is very obvious when comparing the two approaches in TypeScript:

const doThingsWithValidation = async function (options: unknown): Promise<void> {

  // This throws, if the options are not valid.

  const typedOptions = options as Options;

  doSomethingWithAnOption(typedOptions.someOption);

const doThingsWithParsing = async function (options: unknown): Promise<Result<void, Error>> {

  // This parses the options and unwraps them, throwing if they were invalid.

  // If invalid options were something our program could handle, we would not

  // want to throw here and instead handle the error appropriately.

  // In this example we want the function to throw, if the options are invalid.

  const typedOptions = parseOptions(options).unwrapOrThrow();

In the second example, the `typedOptions` contained in the `Result` returned from the `parseOptions` call already have the type that we expect them to have and we don't have to assert them or assign them to a new variable in any way. This combines better support from the TypeScript compiler with better error handling from [`defekt`](https://github.com/thenativeweb/defekt/).

First you need to integrate validate-value into your application:

const { parse, Parser } = require('validate-value');

If you use TypeScript, use the following code instead:

import { parse, Parser } from 'validate-value';

Then, create a new instance and provide a [JSON schema](https://json-schema.org/learn/getting-started-step-by-step.html) that you would like to use for parsing:

If you are using TypeScript, you will want to provide a type for the parsed value:

Afterwards, you may use the `parse` function to parse a value:

const parsedValue = result.unwrapOrThrow();

    // The user object did not match the parser's schema. This should be handled.

    // The user object was parsed successfully and the result's value can now be used.

    doSomethingWithUser(parseResult.value);

After parsing, `parsedValue` will have the type `User`, since it was passed to the parser upon construction.

After parsing, the value in the returned `Result` will have the type `User`, since it was passed to the parser upon construction.

For details on the error handling in the example above, check the [documentation of the `Result` type in `defekt`](https://github.com/thenativeweb/defekt#using-result).

By default, the error message uses `value` as identifier and `.` as the separator for the object that is parsed, but sometimes you may want to change this. Therefor, provide the desired identifier and separator as second parameter to the `parse` function:

value.parse(user, { valueName: 'person', separator: '/' });

const parseResult = parser.parse(user, { valueName: 'person', separator: '/' });

For convenience, there is also the `parse` function, which skips the creation of a parser instance. You can use this if you're only going to use a schema for validation once. Otherwise, it is recommended to first create a parser instance, since then the JSON schema is only compiled once:

const { parse } = require('validate-value');

### Verifying that a variable is of a specific type

To verify that a variable is of a specific type, use the `isOfType` function. Hand over the value you would like to verify, and a JSON schema describing that type. The function returns `true` if the given variable matches the schema, and `false` if it doesn't:

const { isOfType } = require('validate-value');

When using TypeScript, you may even specify a generic type parameter, and use the function as a type guard:

import { isOfType, JsonSchema } from 'validate-value';

<a name="footnote-1">1:</a> ["Parse, don't validate", Alexis King, 2019](https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/).

To run quality assurance for this module use [roboter](https://www.npmjs.com/package/roboter):

		{
		"name": "validate-value",
		"version": "9.1.7",
		"version": "9.2.0",
		"description": "validate-value validates values against JSON schemas.",
		@@ -5,0 +5,0 @@ "contributors": [

		@@ -97,3 +97,3 @@ # validate-value

		```javascript
		```typescript
		const user = {
		@@ -104,8 +104,16 @@ username: 'Jane Doe',

		const result = parser.parse(user);
		const parsedValue = result.unwrapOrThrow();
		const parseResult = parser.parse(user);

		if (parseResult.hasError()) {
		// The user object did not match the parser's schema. This should be handled.
		} else {
		// The user object was parsed successfully and the result's value can now be used.
		doSomethingWithUser(parseResult.value);
		}
		```

		After parsing, `parsedValue` will have the type `User`, since it was passed to the parser upon construction.
		After parsing, the value in the returned `Result` will have the type `User`, since it was passed to the parser upon construction.

		For details on the error handling in the example above, check the [documentation of the `Result` type in `defekt`](https://github.com/thenativeweb/defekt#using-result).

		## Configuring the parser
		@@ -115,3 +123,3 @@

		```javascript
		```typescript
		const user = {
		@@ -122,3 +130,3 @@ username: 'Jane Doe',

		value.parse(user, { valueName: 'person', separator: '/' });
		const parseResult = parser.parse(user, { valueName: 'person', separator: '/' });
		```
		@@ -130,6 +138,6 @@

		```javascript
		const { parse } = require('validate-value');
		```typescript
		import { parse } from 'validate-value';

		parse(user, {
		const parseResult = parse<User>(user, {
		type: 'object',
		@@ -136,0 +144,0 @@ properties: {

		@@ -0,1 +1,8 @@
		# [9.2.0](https://github.com/thenativeweb/validate-value/compare/9.1.7...9.2.0) (2022-01-17)


		### Features

		* Improve readme. ([#405](https://github.com/thenativeweb/validate-value/issues/405)) ([98687b8](https://github.com/thenativeweb/validate-value/commit/98687b82c7b8210e8e8255dc2b170b7b306cf469))

		## [9.1.7](https://github.com/thenativeweb/validate-value/compare/9.1.6...9.1.7) (2021-12-07)
		@@ -2,0 +9,0 @@

Improved metrics