👀 Sniffly

Value Checking Utilities for JavaScript

A lightweight TypeScript utility library for performing common type-safe value checks with type narrowing.

Install

npm i sniffly

Functions

iterHasItems( value )

Checks that an iterable is not empty

⚙️ Arguments:

value - object having a length attribute

dictHasEntries( value )

Checks that a dictionary is not empty

⚙️ Arguments:

value - key/value pair dictionnary

isBool( value )

Checks that the value is a boolean

⚙️ Arguments:

value - unknown value to check

isNumber( value, options? )

Checks that the value is a number satisfying optionnal specifications
Remark:
NaN is not considered as a valid number

⚙️ Arguments:

value - unknown value to check
options (dict) - optionnal additionnal specifications
options.positive (boolean) - checks number is > 0
options.min (number) - checks number is >= min
options.max (number) - checks number is <= max

isString( value, options? )

Checks that the value is a string satisfying optionnal specifications

⚙️ Arguments:

value - unknown value to check
options (dict) - optionnal additionnal specifications
options.nonEmpty (boolean) - checks that string is not empty
options.regexPattern (RegExp) - checks that string matches pattern

isArray( value, options? )

Checks that the value is an array satisfying optionnal specifications

⚙️ Arguments:

value - unknown value to check
options (dict) - optionnal additionnal specifications
options.nonEmpty (boolean) - checks that the array has items
options.itemType (string literal) - check type of array's items, following values are accepted:

• "unknown" (default) - items aren't checked
• "any" - items aren't checked
• "string" - string items only
• "number" - number items only
• "boolean" - boolean itemps only
• "array" - Array<unknown> items only
• "dict" - Record<string, unknown> items only

isDict( value, options? )

Checks that the value is a key/value pair dictionnary satisfying optionnal specifications
Remark:
Only allows objects directly created from {} or Object.create(Object.prototype).
Are considered invalid:

• Objects built from classes like const obj = new Foo() or built-ins like Array, Map, Set or Date
• Objects with no prototype like const obj = Object.create(null)

⚙️ Arguments:

value - unknown value to check
options (dict) - optionnal additionnal specifications
options.nonEmpty (boolean) - checks that the dictionnary has entries
options.keys (string array) expected keys that should be present in the dict
options.itemType (string literal) - check type of entries, following values are accepted:

• "unknown" (default) - entries aren't checked
• "any" - entries aren't checked
• "string" - string entries only
• "number" - number entries only
• "boolean" - boolean entries only
• "array" - Array<unknown> entries only
• "dict" - Record<string, unknown> entries only

Types

Dict_T<EntriesType>

Type of key/value pair dictionnary, with a string key. EntriesType generic represents the type of the entries of the dictionnary.

Example

const data: Dict_T<number> = { 'a': 1, 'b': 2 }