README.md

badbadnotgood

Functional validation, built for composition.

Usage

import {
  all,
  any,
  onlyIf,
  not,
  divisibleBy
  equals,
  minLength,
} from 'badbadnotgood'

// Simple validation
const isFoo = equals('foo')
isFoo('foo') // { isValid: true, messages: [] }
isFoo('bar') // { isValid: false, messages: [] }

// With validation messages
const isBar = equals('bar', 'Value must be "bar"')
isFoo('foo') // { isValid: false, messages: ['Value must be "bar"'] }
isFoo('bar') // { isValid: true, messages: [] }

// Negated
const isNotFoo = not(equals('foo'), 'Value must not be "foo"')
isNotFoo('foo') // { isValid: false, messages: ['Value must not be "foo"']}
isNotFoo('bar') // { isValid: true, messages: [] }

// Composed, with single message
const isFooOrBar = any(
  [equals('foo'), equals('bar')],
  'Value must be "foo" or "bar"'
)
isFooOrBar('foo') // { isValid: true, messages: [] }
isFooOrBar('baz') // { isValid: false, messages: ['Value must be "foo" or "bar"'] }

// Composed, with multiple messages
const isDivisibleBy3And4 = all([
  divisibleBy(3, 'Not divisible by 3'),
  divisibleBy(4, 'Not divisible by 4')
])
isDivisibleBy3And4(12) // { isValid: true, messages: [] }
isDivisibleBy3And4(6) // { isValid: false, messages: ["Not divisible by 4"] }
isDivisibleBy3And4(1) // { isValid: false, messages: ["Not divisible by 3", "Not divisible by 4"] }

// Conditional validation
const atLeast6CharsUnlessFoo = onlyIf(
  not(equals('foo')),
  minLength(6, 'Must be at least 6 characters')
)
atLeast6CharsUnlessFoo('foo') // { isValid: true, messages: [] }
atLeast6CharsUnlessFoo('bar') // { isValid: false, messages: ["Must be at least 6 characters"] }
atLeast6CharsUnlessFoo('foobar') // { isValid: true, messages: [] }

// Arrays
const allAreFoo = forEach(equals('foo', 'Item is not "foo"'), 'All items must be "foo"')
allAreFoo(['foo']) // { isValid: true, messages: [] }
allAreFoo(['foo', 'bar']) // { isValid: false, messages: ['All items must be "foo"', { index: 1, messages: ['Item is not "foo"] }] }