Guard

Guards - or input validation - is a concept in Typescript which allows you to easily ensure specific types. Besides being a great assistance when authoring your code in Typescript, they have the added benefit of being preserved during the transpilation to Javascript, which means your validations will become part of the 'compiled' Javascript. This solves an important issue with Typescript based projects at runtime, as the integrity of the data will still be guaranteed by your Guards.

For pure Javascript developers this is good news, as these Guards easily let you validate your variables too.

Installation

npm install --save @konfirm/guard

Or use your favorite package manager to install @konfirm/guard

API

Exports

name	type
all	function
any	function
assert	function
assertion	function
is	function
isArray	function
isArrayOfSize	function
isArrayOfType	function
isBigInt	function
isBoolean	function
isFloat	function
isFunction	function
isGreater	function
isGreaterOrEqual	function
isInstanceOf	function
isInteger	function
isKey	function
isKeyOfType	function
isLess	function
isLessOrEqual	function
isNULL	function
isNegative	function
isNumber	function
isObject	function
isOptionalKeyOfType	function
isPositive	function
isStrictStructure	function
isString	function
isStringWithPattern	function
isStructure	function
isSymbol	function
isUndefined	function
not	function
Float	Type alias
Guard	Type alias
Integer	Type alias
Negative	Type alias
Positive	Type alias
StringWithPattern	Type alias
Validator	Type alias

all

▸ all<T>(...checks): Guard<T>

Create a guard verifying the given value matches all of the validators

Parameters

Name	Type
...checks	[Validator, ...<Validator>]

Returns

Guard<T>

any

▸ any<T>(...checks): Guard<T>

Create a guard verifying the given value matches any of the validators

Parameters

Name	Type
...checks	[Validator, ...<Validator>]

Returns

Guard<T>

assert

▸ assert<T>(value, message, ...rules): value is T

Guard asserting the given value to match the conditions or throw an AssertionError otherwise

Parameters

Name	Type
value	any
message	string
...rules	[Validator, ...<Validator>]

Returns

value is T

assertion

▸ assertion<T>(message, ...rules): Guard<T>

Create an assertion guard, throwing an AssertionError with the provided message if any validator fails

Parameters

Name	Type
message	string
...rules	[Validator, ...<Validator>]

Returns

Guard<T>

is

▸ is<T>(type): Guard<T>

Create a guard verifying the given value matches the specified type

Parameters

Name	Type
type	"string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"

Returns

Guard<T>

isArray

▸ Const isArray(value): value is unknown[]

Guard verifying the value is a array

Parameters

Name	Type
value	any

Returns

value is unknown[]

isArrayOfSize

▸ isArrayOfSize<T>(min, max?): Guard<T>

Guard verifying the value to be an array with a length between the given boundaries

Parameters

Name	Type	Default value
min	number	undefined
max	number	Infinity

Returns

Guard<T>

isArrayOfType

▸ isArrayOfType<T>(...validators): Guard<T>

Guard verifying the value to be an array containing only elements matching the validators

Parameters

Name	Type
...validators	[Validator, ...<Validator>]

Returns

Guard<T>

isBigInt

▸ Const isBigInt(value): value is BigInt

Guard verifying the value is a bigint

Parameters

Name	Type
value	any

Returns

value is BigInt

isBoolean

▸ Const isBoolean(value): value is boolean

Guard verifying the value is a boolean

Parameters

Name	Type
value	any

Returns

value is boolean

isFloat

▸ isFloat<T>(value): value is T

Guard verifying the value to be a float number

Type parameters

Name	Type
T	number

Parameters

Name	Type
value	any

Returns

value is T

isFunction

▸ Const isFunction(value): value is Function

Guard verifying the value is a function

Parameters

Name	Type
value	any

Returns

value is Function

isGreater

▸ isGreater<T>(than): Guard<T>

Create a guard matching numbers greater than the provided value

Type parameters

Name	Type
T	number

Parameters

Name	Type
than	number

Returns

Guard<T>

isGreaterOrEqual

▸ isGreaterOrEqual<T>(than): Guard<T>

Create a guard matching numbers greater than or equal to the provided value

Type parameters

Name	Type
T	number

Parameters

Name	Type
than	number

Returns

Guard<T>

isInstanceOf

▸ isInstanceOf(type): Guard<typeof type>

Creates a guard verifying the value is an object and an instance of the given class

Parameters

Name	Type
type	(...args: any[]) => unknown

Returns

Guard<typeof type>

isInteger

▸ isInteger<T>(value): value is T

Guard verifying the value to be an integer number

Type parameters

Name	Type
T	number

Parameters

Name	Type
value	any

Returns

value is T

isKey

▸ isKey<T>(key): Guard<T>

Creates a guard verifying the value is an object and has the given key

Parameters

Name	Type
key	Key

Returns

Guard<T>

isKeyOfType

▸ isKeyOfType<T>(key, ...validators): Guard<T>

Creates a guard verifying the value is an object and has the given key matching the validators

Parameters

Name	Type
key	Key
...validators	Validator[]

Returns

Guard<T>

isLess

▸ isLess<T>(than): Guard<T>

Create a guard matching numbers less than the provided value

Type parameters

Name	Type
T	number

Parameters

Name	Type
than	number

Returns

Guard<T>

isLessOrEqual

▸ isLessOrEqual<T>(than): Guard<T>

Create a guard matching numbers less than or equal to the provided value

Type parameters

Name	Type
T	number

Parameters

Name	Type
than	number

Returns

Guard<T>

isNULL

▸ Const isNULL(value): value is null

Guard verifying the value is a null

Parameters

Name	Type
value	any

Returns

value is null

isNegative

▸ isNegative<T>(value): value is T

Guard verifying the value to be a negative number

Type parameters

Name	Type
T	number

Parameters

Name	Type
value	any

Returns

value is T

isNumber

▸ Const isNumber(value): value is number

Guard verifying the value is a number

Parameters

Name	Type
value	any

Returns

value is number

isObject

▸ Const isObject(value): value is unknown

Guard verifying the value is a object

Parameters

Name	Type
value	any

Returns

value is unknown

isOptionalKeyOfType

▸ isOptionalKeyOfType<T>(key, ...validators): Guard<T>

Creates a guard verifying the value is an object and doesn't have the key or has the given key matching the validators

Parameters

Name	Type
key	Key
...validators	Validator[]

Returns

Guard<T>

isPositive

▸ isPositive<T>(value): value is T

Guard verifying the value to be a positive number

Type parameters

Name	Type
T	number

Parameters

Name	Type
value	any

Returns

value is T

isStrictStructure

▸ isStrictStructure<T>(struct, ...options): Guard<T>

Creates a guard verifying the value is an object matching exactly the structure

Parameters

Name	Type
struct	Object
...options	(Key | Key[])[]

Returns

Guard<T>

isString

▸ Const isString(value): value is string

Guard verifying the value is a string

Parameters

Name	Type
value	any

Returns

value is string

isStringWithPattern

▸ isStringWithPattern<T>(pattern): Guard<T>

Guard verifying the value to be a string which matches the given pattern

Type parameters

Name	Type
T	string

Parameters

Name	Type
pattern	RegExp

Returns

Guard<T>

isStructure

▸ isStructure<T>(struct, ...options): Guard<T>

Creates a guard verifying the value is an object matching at least the structure

Parameters

Name	Type
struct	Struct<Validator>
...options	(Key | Key[])[]

Returns

Guard<T>

isSymbol

▸ Const isSymbol(value): value is Symbol

Guard verifying the value is a symbol

Parameters

Name	Type
value	any

Returns

value is Symbol

isUndefined

▸ Const isUndefined(value): value is undefined

Guard verifying the value is a undefined

Parameters

Name	Type
value	any

Returns

value is undefined

not

▸ not<T>(...checks): Guard<T>

Create a guard verifying the given value matches none of the validators

Parameters

Name	Type
...checks	[Validator, ...<Validator>]

Returns

Guard<T>

Type aliases

Float

Ƭ Float: number

Guard

Ƭ Guard<T>: (value: any) => value is T

Type declaration

▸ (value): value is T

Parameters

Name	Type
value	any

Returns

value is T

Integer

Ƭ Integer: number

Negative

Ƭ Negative: number

Positive

Ƭ Positive: number

StringWithPattern

Ƭ StringWithPattern: string

Validator

Ƭ Validator: (value: any) => boolean

Type declaration

▸ (value): boolean

Parameters

Name	Type
value	any

Returns

boolean

License

MIT License Copyright (c) 2021-2023 Rogier Spieker (Konfirm)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.