@bemoje/is

Type checking and validation utilities with composable validators and detailed error reporting.

Exports

• IsArrayWhereEach: Creates a validator function that checks whether the input is an array where all elements are valid according to every validator provided.
• IsFileExt.
• IsLength: Creates a function that validates if the length of the input is equal to the specified length. The returned function accepts any value with a 'length' property and is named 'isLen' concatenated with the specified length.
• ValidatorError: Custom error class for validation failures, providing detailed information about the input, expected outcome, and cause of failure.
• createGtValidator: Creates a validator function that checks if a value is a number greater than the specified limit.
• createGteValidator: Creates a validator function that checks if a value is a number greater than or equal to the specified limit.
• createLtValidator: Creates a validator function that checks if a value is a number less than the specified limit.
• createLteValidator: Creates a validator function that checks if a value is a number less than or equal to the specified limit.
• ensureThat. If validation fails, an error is thrown with details about the failure. Validators can return strings indicating the reason for failure, which will be included in the error message.
• isArray: Checks if the provided value is an array.
• isChar: Determines whether a string is a single character.
• isClass: Checks if the given value is a constructor function using 'class' syntax. WARNING: If the running code is minified or mangled, this function may not work as expected. However, it should be resistant to minification/mangling if the 'class' keyword is present in the first line of the function.
• isConstructor: Checks if the given value is a valid constructor function.
• isDefined: This function checks if a value is defined or not. It performs a strict comparison against undefined.
• isDigit: Returns true if the given character is a digit between 0 and 9.
• isDigits: Returns true if the given string is a string of digits between 0 and 9.
• isEven: Checks if a number is even.
• isHex: Checks if a string is a hexadecimal number. Understands prefixes for hex colors, hex decimal and regexp unicode hex.
• isHexOrUnicode: Checks if a given string is a hexadecimal or unicode.
• isIntRange: Determine whether the input is an array of two integers in ascending order.
• isInteger: Checks if the provided number is an integer.
• isLen2: Determine whether the input has length of 2.
• isNamedFunction: Checks if the provided value is a named function.
• isNamedFunctionArray: Checks if the provided value is an array containing only named functions.
• isNegativeInteger: Checks if a given number is a negative integer.
• isNegativeNumber: Checks if a given number is negative or zero.
• isNonZeroNegativeInteger: Checks if a given number is a negative non-zero integer.
• isNonZeroNegativeNumber: Checks if a given value is a negative number less than zero.
• isNonZeroPositiveInteger: Checks if a given number is a positive non-zero integer.
• isNonZeroPositiveNumber: Checks if a given value is a positive number greater than zero.
• isNumArrayAscending: Determine whether the input is an array of numbers in ascending order. Duplicate values are allowed.
• isNumericString: Checks if a given string is numeric.
• isObject.
• isObjectType.
• isOdd: Checks if a number is odd.
• isPosIntArray integer array.
• isPosIntRange: Checks if the input is an array of exactly two positive integers in ascending order, representing a valid range.
• isPositiveInteger: Checks if a given number is a positive integer.
• isPositiveNumber.
• isPrototype: Checks if the given value is a prototype object
• isStringArray: Determine whether the input is a string array.
• isStringWithNoSpacesOrDashes: Checks if the provided value is a string that contains no spaces or dashes.
• isUniqueNumArrayAscending: Determine whether the input is an array of numbers in ascending order. Duplicate values are not allowed.
• isValidNumber.

Installation

npm install @bemoje/is

Usage

Basic Type Guards

import { isArray, isInteger, isObject, isPositiveNumber, isEven } from '@bemoje/is'

isArray([1, 2, 3]) // true
isInteger(42) // true
isObject({ a: 1 }) // true
isPositiveNumber(-5) // false
isEven(4) // true

Validate with ensureThat

Assert that values pass validation, throwing detailed errors on failure:

import { ensureThat, isInteger, isPositiveNumber } from '@bemoje/is'

ensureThat(42, isInteger)
// 42

ensureThat(-3, [isInteger, isPositiveNumber])
// throws ValidatorError with cause: { isPositiveNumber: false }

Create Composite Validators

import { IsArrayWhereEach, isInteger, isPositiveNumber } from '@bemoje/is'

const isPosIntArray = IsArrayWhereEach([isInteger, isPositiveNumber])

isPosIntArray([1, 2, 3]) // true
isPosIntArray([1, -2, 3]) // false
isPosIntArray('hello') // false

Length Validation

import { IsLength } from '@bemoje/is'

const isLen3 = IsLength(3)
isLen3([1, 2, 3]) // true
isLen3('abc') // true
isLen3([1, 2]) // false

File Extension Validation

import { IsFileExt } from '@bemoje/is'

const isTs = IsFileExt('ts')
isTs('index.ts') // true
isTs('index.js') // false

Comparison Validators

import { createGtValidator, createLteValidator } from '@bemoje/is'

const isGt10 = createGtValidator(10)
isGt10(15) // true
isGt10(5) // false

const isLte100 = createLteValidator(100)
isLte100(100) // true
isLte100(101) // false

Validation Error Details

import { ValidatorError } from '@bemoje/is'

try {
  ensureThat(-3, [isInteger, isPositiveNumber])
} catch (e) {
  if (e instanceof ValidatorError) {
    console.log(e.input) // -3
    console.log(e.expected) // true
    console.log(e.cause) // { isPositiveNumber: false }
  }
}