Extendable library for typecasting.

Usage

Import

Examples

import * as a from 'alwz';
// or
const a = require('alwz');

Types

• See: presets

convert data with presetted converters

Examples

a.byte('3'); // 3
a.short(false); // 0
a.int(true); // 1
a.uint(Infinity); // 4294967295
a.long(NaN); // 0
a.long(['1', '2', '3']); // 1 | ['1','2','3'] => '1' => 1
a.array('abc'); // ['abc']
a.array([123, 'abc', {}, Math.max]); // [123, 'abc', {}, Math.max]

Structures

• See: utils

construct complex data

Examples

ensure an array output

const array = a.utils.array;
const ArrayOfUByte = array(a.ubyte);
ArrayOfUByte([undefined, true, 2.3, '4', Infinity]); // [0, 1, 2, 4, 255]

simplify multidimensional arrays processing

const array = a.utils.array;

const Bytes3dArray = array(array(array(a.byte)));

Bytes3dArray(1); // [[[1]]];
Bytes3dArray([[[null, NaN, 'a'], [true, '2', 3]], [[Infinity]]]); // [[[0, 0, 0], [1, 2, 3]], [[127]]];

create tuples

const tuple = a.utils.tuple;
const PairOfUint = tuple([a.uint, a.uint]);
PairOfUint(['abc', 3.5, 100]); // [0, 3]

const PairOfNumbers = tuple([Number, Number]);
PairOfNumbers(['abc', 3.5, 100]); // [NaN, 3.5]

Transformations

• See: Converter

create custom converters

Examples

extend an existing converter

// make boolean smarter
const bool = a.converters.get('boolean')
  .clone()
  .string(function(v) { // string input processing
    if (v === 'true' || v === 'yes') {
      return true;
    } else if (v === 'false' || v === 'no') {
      return false;
    } else {
      return this.types.number(Number(v));
    }
  })
  .convert;

bool('yes'); // true
bool('no'); // false
bool('false'); // false

parse colon-separated number/string records

const PathArray = a.converters.get('array')
  .clone()
  .string((i) => [...i.matchAll(/\/(\w+)/g)].map((i) => i[1]))
  .convert;

const DSV2Tuple = a.utils.tuple(
  [String, String, Number, Number, String, PathArray, PathArray],
  a.converters.get('array')
    .clone()
    .string((i) => i.split(':'))
    .convert
);

const input = 'user:12345:1000:1000:ordinar user:/home/user:/bin/sh';
DSV2Tuple(input); // ['user', '12345', 1000, 1000, 'ordinar user', ['home', 'user'], ['bin', 'sh']];

Selector

dynamically select convert function (based on predefined converters)

Examples

a.to('int')('24.5'); // 24
a.to('byte')(Infinity); // 127
a.to('bigint')('42.5'); // 42n

Converters

registry of predefined converters

Examples

// get list of predefined converters
Array.from(a.converters.keys()); // ['boolean', 'byte', 'int', 'long', 'double', 'string', ...];

// retrieving with existence check
const Num = a.converters.converter('number'); // Converter<number>
const Str = a.converters.converter('string'); // Converter<string>
a.converters.converter('123'); // Error

// direct retrieving
const Arr = a.converters.get('array'); // Converter<Array>
const Unknown = a.converters.get('123'); // undefined

Predicates

• See: is

data type checks

Examples

const { is } = a;

is.void(0); // false
is.void(null); // true
is.value(null); // false
is.value(0); // true
is.ubyte(255); // true
is.int(Infinity); // false
is.object(null); // false
is.Iterable(new Set()); // true

Checks

• See: Is

create readable check functions

Examples

const { Is } = a;

const isAlphaOrBeta = Is.variant(['Alpha', 'Beta']);
isAlphaOrBeta('Alpha'); // true;
isAlphaOrBeta('Gamma'); // false;

class X {}
class Y extends X {}

const isX = Is.instance(X);
isX(new X); // true
isX(new Y); // true
isX({}); // false

Errors

• See: ErrorValue

create informative errors

Examples

add additional value to an error

const { ErrorValue } = a;
const inc = (input) => typeof input === 'number'
  ? input + 1
  : new ErrorValue('invalid list', { input, date: Date.now() }).throw();

inc('1'); // Error { message: 'invalid number', value: { input: '1', date: 946684800000 } }

intercept and wrap thrown ones

try {
 throw new Error('oops, something went wrong');
} catch (error) {
 throw new ErrorValue('urgent message', { data: 'some additional data' }, { cause: error });
}

presets

boolean

Examples

boolean.convert('abc'); // true
boolean.convert(Symbol.for('')); // false
boolean.convert([]); // false
boolean.convert([0]); // false
boolean.convert([false, true]); // false
boolean.convert([123]); // true

number

Examples

number.convert(Infinity); // Infinity
number.convert('42'); // 42
number.convert('abc'); // NaN
number.convert(Symbol.for('42')); // 42
number.convert(new Date('1970-01-01T00:00:00.042Z')); // 42
number.convert(['42']); // 42
number.convert([ [ [ 42 ] ] ]); // 42
number.convert(new Date('1970-01-01T00:00:00.999Z')); // 999

integers

|--------|------------------|------------------|
| type   |              min |              max |
|--------|------------------|------------------|
| byte   |             -128 |              127 |
| short  |           -32768 |            32767 |
| int    |      -2147483648 |       2147483647 |
| long   | MIN_SAFE_INTEGER | MAX_SAFE_INTEGER |
|--------|------------------|------------------|
| ubyte  |                0 |              255 |
| ushort |                0 |            65535 |
| uint   |                0 |       4294967295 |
| ulong  |                0 | MAX_SAFE_INTEGER |
|--------|------------------|------------------|

Examples

int.convert(undefined); // 0
int.convert(null); // 0
int.convert(NaN); // 0
int.convert('abc'); // 0
int.convert(true); // 1
int.convert(42.5); // 42
int.convert('42.5'); // 42
int.convert(['42.5']); // 42
int.convert(Symbol.for('42.5')); // 42
int.convert(new Date('1970-01-01T00:00:00.042Z')); // 42
int.convert(new Date(NaN)); // 0

signed

cast to byte, short (2 bytes), int (4 bytes) or long (8 bytes)

Examples

byte.convert(128); // 127
byte.convert(Infinity); // 127
byte.convert(-Infinity); // -128
short.convert(Infinity); // 32767
short.convert(-Infinity); // -32768
int.convert(Infinity); // 2147483647
int.convert(-Infinity); // -2147483648
long.convert(Infinity); // MAX_SAFE_INTEGER
long.convert(-Infinity); // MIN_SAFE_INTEGER

unsigned

cast to ubyte, ushort (2 bytes), uint (4 bytes) or ulong (8 bytes)

Examples

ubyte.convert(-7); // 0
ubyte.convert('a'); // 0
ubyte.convert(Infinity); // 255
ubyte.convert(-Infinity); // 0
ushort.convert(Infinity); // 65535
ushort.convert(-Infinity); // 0
uint.convert(Infinity); // 4294967295
uint.convert(-Infinity); // 0
ulong.convert(Infinity); // MAX_SAFE_INTEGER
ulong.convert(-Infinity); // 0

double

Examples

double.convert('42.5'); // 42.5
double.convert(Infinity); // Number.MAX_VALUE
double.convert(NaN); // 0

bigint

Examples

bigint.convert(42.5); // 42n
bigint.convert('42'); // 42n
bigint.convert('42.5'); // 0n
bigint.convert(Symbol.for('42')); // 42n
bigint.convert(new Date('1970-01-01T00:00:00.999Z')); // 999n

string

Examples

string.convert(); // ''
string.convert(null); // ''
string.convert(false); // ''
string.convert(true); // ' '
string.convert(42.5); // '42.5'
string.convert([1, 2, 3]); // '1'
string.convert(Symbol.for('42')); // '42'
string.convert(new Date('1970-01-01T00:00:00.999Z')); // '1970-01-01T00:00:00.999Z'

symbol

Examples

symbol.convert(false); // Symbol('')
symbol.convert(42.5); // Symbol('42.5')
symbol.convert('42.5'); // Symbol('42.5')
symbol.convert([1.5, 2, 3]); // Symbol('1.5')
symbol.convert(new Date('1970-01-01T00:00:00.999Z')); // Symbol('1970-01-01T00:00:00.999Z')

array

Examples

array.convert(); // []
array.convert(null); // []
array.convert(false); // [false]
array.convert(123); // [123]
array.convert('1,2,3'); // ['1,2,3']
array.convert(new Set([1, 2, 3])); // [1, 2, 3]
array.convert(new Map([[1, 2], [3, 4], [5, 6]])); // [[1, 2], [3, 4], [5, 6]]

fn

Examples

fn.convert((a, b) => a + b); // (a, b) => a + b
fn.convert(123); // () => 123

date

Examples

date.convert(111); // Date('1970-01-01T00:00:00.111Z')
date.convert([222, 333]); // Date('1970-01-01T00:00:00.222Z')
date.convert('abc'); // Date(NaN)

object

Examples

object.convert(undefined); // {}
object.convert(null); // {}
object.convert(false); // Boolean { false }
object.convert(1); // Number { 1 }
object.convert('2'); // String { 2 }
object.convert([1, '2', 3n]); // [1, '2', 3n]

map

Examples

map.convert([ [true, 1], 2, '3']); // Map { [true, 1] }

weakmap

Examples

weakmap.convert([ [Boolean, 'bool'], [Number, 'num'], [String, 'str'], [true, 1], 2, '3']); // WeakMap { [Boolean, 'bool'], [Number, 'num'], [String, 'str'] }

set

Examples

set.convert([1, '2', 3]); // Set {1, '2', 3}

weakset

Examples

weakset.convert([Boolean, Number, String, true, 2, '3']); // WeakSet { Boolean, Number, String }

promise

Examples

promise.convert(Promise.resolve(1)); // Promise { 1 }
promise.convert(42); // Promise { 42 }

utils

extra utils functions

Examples

const { array, tuple, range, variant, object, dictionary } = a.utils;

array

constrain data to an array elements of a given type

Parameters

• conversion Conversion<any, OUTPUT> item conversion
• initiator Conversion<any, Array<any>> input data initial conversion (optional, default presets.array.convert)

Examples

const Numbers = array(Number);

Numbers(); // []
Numbers([]); // []
Numbers([true, 2, "3", {}]); // [1, 2, 3, NaN]

sparse arrays behavior

// Be aware of sparse arrays behavior - conversion is not performed for empty items
numArray[1, , 3] // [1, , 3]

Returns Conversion<any, Array<OUTPUT>>

tuple

constrain data to a tuple with given types

Parameters

• conversions Array<Conversion<any, any>> tuple elemets conversions
• initiator Conversion<any, Array<any>> input data initial conversion (optional, default presets.array.convert)

Examples

const NumStrBool = tuple([Number, String, Boolean]);

NumStrBool(); // [NaN, 'undefined', false]
NumStrBool(null); // [NaN, 'undefined', false]
NumStrBool([]); // [NaN, '', false]
NumStrBool('5'); // [5, 'undefined', false]
NumStrBool(['1', '2', '3']); // [1, '2', true]

Returns Conversion<any, Array<any>>

range

constrain variable value within a given range

Parameters

• lower OUTPUT lower range border (optional, default -Number.MAX_VALUE)
• upper OUTPUT upper range border (optional, default Number.MAX_VALUE)
• fallback Fallback<OUTPUT> fallback value generator
• conversion Conversion<any, OUTPUT> input data conversion (optional, default presets.double.convert)

Examples

const range37 = range(3, 7);

range37(1); // 3
range37(5); // 5
range37(9); // 7


const range37WithCustomFallback = range(3, 7, () => -1);

range37WithCustomFallback(1); // -1
range37WithCustomFallback(5); // 5
range37WithCustomFallback(9); // -1


const rangeString = range('k', 'w', undefined, String);

rangeString('a'); // k
rangeString('n'); // n
rangeString('z'); // w

Returns Conversion<any, OUTPUT>

variant

constrain variable to given variants

Parameters

• values Array<OUTPUT> valid values list
• fallback Fallback<OUTPUT> fallback value generator (optional, default ()=>values[0])
• conversion Conversion<any, OUTPUT> input data conversion (optional, default presets.double.convert)

Examples

const oneOf123 = variant([1, 2, 3]);

oneOf123(1); // 1
oneOf123(2); // 2
oneOf123(3); // 3
oneOf123(4); // 1
oneOf123(-5); // 1


const oneOf123WithCustomFallback = variant([1, 2, 3], () => -1);

oneOf123WithCustomFallback(4); // -1


oneOf123Strict([1, 2, 3], () => {
  throw new Error('invalid input');
});
oneOf123Strict(4); // throws an Error


const oneOfAB = variant(['a', 'b'], (i) => ['a', 'b'][i], String);

oneOfAB('a'); // 'a'
oneOfAB('b'); // 'b'
oneOfAB(0); // 'a'
oneOfAB(1); // 'b'

Returns Conversion<any, OUTPUT>

object

cast data into an object with a given schema

Parameters

• schema Record<string, Conversion<any, OUTPUT>>
• conversion Conversion<any, OUTPUT> input data conversion (optional, default presets.object.convert)

Examples

const obj = object({
  a: a.ubyte,
  b: array(object({
    c: a.int,
    d: a.string,
  })),
});

obj(undefined); // { a: 0, b: [] }
obj({ a: 999, b: [{ c: 2.5, d: 3 }, null] }); // { a: 255, b: [{ c: 2, d: '3' }, { c: 0, d: '' }] }

Returns Conversion<any, OUTPUT>

dictionary

cast data into a dictionary

Parameters

• conversion
• initiator Conversion<any, any> input data conversion (optional, default presets.object.convert)

Examples

const dictOfInt = utils.dictionary(a.int);

dictOfInt(undefined); // { }
dictInt({ a: null, b: true, c: '2', d: [3, 4] }); // { a: 0, b: 1, c: 2, d: 3 }

Returns Conversion<any, Record<(string | number), VALUE>>

projection

project data into object according to schema

Parameters

• schema Schema

Examples

const schema = {
  // shallow element
  a: (source) => source.x + 1,
  // nested schema
  b: {
    c: (source) => source.x + 2,
  },
  // options ( second argument )
  d: (source, options) => options,
  // mid-process result access
  e: (source, options, target) => { target._e = source.x + 3; },
  // call context
  f: function() { return this; },
};

const project = projection(schema);
const reshape = project(schema);
const source = { x: 1 };
const options = { z: 5 };
const context = { y: 11 };

project.call(context, source, options);
{
  a: 2,
  b: { c: 3 },
  d: { z: 5 },
  _e: 7, e: undefined,
  f: { y: 11 },
}

Returns Function

is

guard functions (pattern matching check)

undefined

null

void

undefined or null

Examples

is.void(null) // true
is.void(0) // false

value

any value except undefined or null

Examples

is.value(null) // false
is.value(0) // true

boolean

Examples

is.boolean(1) // false
is.boolean(true) // true

number

Examples

is.number(NaN) // true
is.number(Infinity) // true
is.number(1) // true
is.number('1') // false

integers

byte, short, int, long

Examples

is.int(NaN) // false
is.long(Infinity) // false
is.uint(-1) // false
is.uint(1) // true
is.uint(1.5) // false

floats

double

Examples

is.double(NaN) // false
is.double(Infinity) // false
is.double(1.5) // true

bigint

string

symbol

function

object

any object (null excluded)

Examples

is.object(null) // false
is.object({}) // true

Error

Array

Examples

is.Array({}) // false
is.Array([]) // true

Date

RegExp

Promise

Set

WeakSet

Map

WeakMap

Iterable

can be iterated

Examples

is.Iterable(new Map()); // true
is.Iterable([]); // true
is.Iterable({}); // false

type

Parameters

• type

Examples

const isString = type('string');
isString(1); // false
isString('1'); // true

instance

Parameters

• prototype

Examples

class Test {}
const isTest = instance(Test);
isTest({}); // false
isTest(new Test()); // true

variant

Parameters

• list

Examples

const isVariant = variant([1, 2, 3]);
isVariant(4); // false
isVariant(3); // true

check

Parameters

• guard

Examples

const isOdd = check((v) => v % 2 ? true : false);
isOdd(0); // false
isOdd(1); // true

Converter

converts input data to specific type

• at first checks if conversion is necessary
• attempts conversion based on the input data type
• searches for suitable conversions among registered
• calls a fallback function

Parameters

• is IS<OUTPUT> initial input data type check (predicate). determines if any conversion is necessary
• fallback Fallback<OUTPUT> fallback value generator. runs if none of the available conversions are suitable

Examples

converter creation

const positive = new Converter(
  (input) => typeof input === 'number' && input > 0,
  (input) => input === 0 ? 0.1 : 0.2
);

positive
  .undefined(() => 0.3)
  .boolean((i) => i ? 1 : 0.4)
  .number(function(i) {
    const result = Math.abs(i)
    return this.is(result) ? result : this.fallback(i);
  })
  .string((i) => positive.convert(Number(i)))
  .symbol((i) => positive.convert(Symbol.keyFor(i)))
  .bigint((i) => positive.convert(Number(i)))
  .register(Array.isArray, (i) => positive.convert(i[0]))
  .register((i) => i === null, (i) => 0.5);

positive.convert(1); // 1
positive.convert(0); // 0.1 (fallback)
positive.convert(NaN); // 0.2 (fallback)
positive.convert(undefined); // 0.3 (has own handler)
positive.convert(false); // 0.4 (has own handler)
positive.convert(null); // 0.5 (has own handler)
positive.convert(2n); // 2
positive.convert(-3); // 3
positive.convert('4'); // 4
positive.convert([5, 6]); // 5

conversion with prohibited input types

const converter = new Converter(
  (input) => typeof input === 'number',
  (input) => {
    throw new Error('unknown input data type:' + input);
  })
  .string((i) => {
    throw new Error('string input is forbidden:' + i);
  })
  .boolean(Number)
  .register(Array.isArray, (i) => converter.convert(i[0]));

converter.convert(true); // 1
converter.convert(2); // 2
converter.convert('3'); // Error
converter.convert([4]); // 4
converter.convert(Promise.resolve(5)); // Error

convert

converts data according to saved conversion rules

Parameters

• input any input data

register

adds conversion function for INPUT type

Parameters

• is IS<INPUT> input data type check (predicate), determines if input can be processed by conversion
• conversion Conversion<INPUT, OUTPUT> INPUT to OUTPUT conversion function

unregister

removes conversion for INPUT type

Parameters

• is IS<INPUT> input type check (predicate)

type

set conversion rule for type name if conversion is defined or unset if undefined

Parameters

• name string one of types (typeof result)
• conversion Conversion?

undefined

conversion rule setter for undefined input

Parameters

• conversion Conversion?

boolean

conversion rule setter for boolean input

Parameters

• conversion Conversion?

number

conversion rule setter for number input

Parameters

• conversion Conversion?

bigint

conversion rule setter for bigint input

Parameters

• conversion Conversion?

string

conversion rule setter for string input

Parameters

• conversion Conversion?

symbol

conversion rule setter for symbol input

Parameters

• conversion Conversion?

clone

Examples

const converter = new Converter(
  (i) => typeof i === 'number',
  () => 0
)
  .undefined(() => 1);

const clone = converter
  .clone()
  .undefined(() => 2);

converter.convert(); // 1
clone.convert(); // 2

ErrorValue

Extends Error

Error with value property

Parameters

• message string?
• value any?
• options any?

Properties

• value any? can be used to store additional cause info

throw

throw this instance of error