Simple functional programming utility & programming helper tools

Simple utility functions that can use browser, node.

Function list

boolean

| name | description | | ------- | ------------------------------ | | isFalse | If argument false, return true | | isTrue | If argument true, return true | | invert | return inverted boolean value |

array

| name | description | | -------- | --------------------------------------------------------------------------------- | | populate | populate array zero base, if you pass second argument true that populate one base | | chunk | array split given size | | last | pick last element from array | | first | pick first element from array | | toArray | make array given argument | | settify | make it set and convert it back to array |

empty

| name | description | | ----------------- | ----------------------------------------------------------------------------------------------------- | | isUndefined | if argument undefiend, return true | | isNotUndefined | if argument not undefined, return true | | isNull | if argument null, return true | | isNotNull | if argument not null, return true | | isNotEmpty | if argument not null and undefined, return true | | isEmpty | if argument null or undefined, return true | | isComplexEmpty | if argument not undefined and null, do additional test isNaN, empty string, empty array, empty object | | isNotComplexEmpty | return inverted value isComplexEmpty |

misc

| name | description | | ----------------- | ----------------------------------------------------- | | typedkey | same work Object.keys, but typed key in Recoed | | getRandomRange | return random value in min and max | | getRandomRangeInt | return random integer value in min and max | | isError | if argument is Error return Error or return undefined |

sleep

| name | description | | ----- | ----------------------- | | sleep | sleep given millisecond |

Custom Utility Types

| name | description | | ------------------ | -------------------------------------- | | TResolvePromise | get type resolved promise | | TResolveArray | get type resolve array | | TNullablePick | convert specific field to nullable | | TNonNullableObject | object type each field to non nullable | | TNonNullablePick | convert specific field to non nullable |

False & True checker

Why need this utility?

import { isFalse } from 'my-easy-fp';

const iamboolean = false;

// this line easily miss in refactoring or changing
if (!iamboolean) {
  console.log('I am execute false-case');
}

// more than better!
if (isFalse(iamboolean)) {
  console.log('I am execute false-case');
}

Empty checker

Why need this utility?

const iamempty?: string | null = undefined;

// this line some boring task
if (iamempty === undefined || iamempty === null || iamempty !== '') {
  console.log('i am empty');
}

// more than better!
if (isComplexEmpty(iamempty)) {
  console.log('i am empty');
}

You need only undefined and null check, use double equal operator.

const iamempty?: string | null = undefined;

// Recently ESLint allow double equal for null check
// see https://eslint.org/docs/latest/rules/eqeqeq#allow-null
if (iamempty == null) {
  console.log('i am empty');
}

Sleep

Why need this utility?

const ms = 1000;

// this line some boring task
await new Promise((resolve) => setTimeout(() => resolve(), ms));

// more than better!
await sleep(ms);

Array

populate, chunk utility here.

// seq is [0,1,2,3,4,5,6,7,8,9]
const seq = populate(10);

// seq is [1,2,3,4,5,6,7,8,9,10]
const seq = populate(10, true);

// chunked is [[1,2],[3,4],[5,6],[7]]
const chunked = chunk([1, 2, 3, 4, 5, 6, 7], 2);

// settify is [ 1, 2, 3, 4 ]
const settified = settify([1, 1, 2, 3, 2, 3, 4]);

// zeroIndex is 1
const zeroIndex = atOrThrow([1, 2, 3], 0);

Type Helper

resolve promise, array. But you can use type-fest or ts-essentials. Recommand use type-fest and tsessentials.

// you can get string | Buffer type
type TResolvedPromiseType = TResolvePromise<ReturnType<typeof fs.promises.readFile>>;

// you can get number type
type TResolvedArrayType = TResolveArray<number[]>;

interface IStudent {
  name: string;
  major: string;
  grade: number;
}

// you can get { name?: string; major?: string; grade: number; }
// converted Omit<IStudent, 'name' | 'major'> & Pick<Partial<IStudent>, 'name' | 'major'>
type TCliArgumentStudent = TNullablePick<IStudent, 'name' | 'major'>;