@hemjs/notions

Utilities for arrays, objects, strings, and more.

Table of contents

• Installation
• Async
  • deadline
  • delay
• Lang
  • isBoolean
  • isClass
  • isEmpty
  • isFunction
  • isNil
  • isNull
  • isNumber
  • isObject
  • isPlainObject
  • isString
  • isSymbol
  • isUndefined
• Object
  • omit
  • pick
• License

Installation

Install with npm:

npm install --save @hemjs/notions

Install with yarn:

yarn add @hemjs/notions

Async

deadline

Creates a promise which will be rejected with DeadlineError when a given delay is exceeded.

Type:

function deadline<T>(
  p: Promise<T>,
  ms: number,
  options?: DeadlineOptions,
): Promise<T>;

Example:

import { deadline } from '@hemjs/notions';

const myPromise = fetch('https://api.example.com/data');

deadline(myPromise, 1000) // Wait for 1 second
  .then((data) => {
    // Handle successful response
  })
  .catch((error) => {
    if (error instanceof DeadlineError) {
      console.error('Promise timed out!');
    } else {
      console.error('Error:', error);
    }
  });

Parameters:

• p: The promise to be wrapped with a deadline.
• ms: The delay in milliseconds before the deadline triggers.
• options: (Optional) An object containing:
  • signal: An AbortSignal object to manually abort the deadline.

Returns:

A new promise that resolves or rejects according to the original promise and the deadline.

Errors:

• If the deadline is met before the original promise resolves, the returned promise is rejected with a DeadlineError.
• If the original promise rejects, the returned promise also rejects with the original promise's rejection reason.

Cancellation:

You can cancel the deadline manually by providing an AbortSignal in the options object and aborting the signal elsewhere in your code.

Notes:

• The catch block within the deadline function does nothing on abort to prevent potential errors due to rejected signals.

delay

Resolves a Promise after a given amount of milliseconds.

Type:

function delay(ms: number, options?: DelayOptions): Promise<void>;

Example:

import { delay } from '@hemjs/notions';

async function doSomethingAfterDelay() {
  await delay(2000); // Wait for 2 seconds
  console.log('Done!');
}

doSomethingAfterDelay();

Parameters:

• ms: The number of milliseconds to wait before resolving the promise.
• options: (Optional) An object containing:
  • signal: An AbortSignal object to manually abort the delay.

Returns:

A promise that resolves after the specified delay, with no data to fulfill.

Errors:

If the delay is aborted using the AbortSignal, the promise is rejected with the reason provided by the signal.

Cancellation:

You can cancel the delay before it completes by providing an AbortSignal in the options object and aborting the signal elsewhere in your code.

Notes:

• The function uses setTimeout internally to create the delay.
• The provided AbortSignal is used to listen for abort events and reject the promise accordingly.

Lang

isBoolean

Determines whether a given value is of type boolean.

Type:

function isBoolean(value?: any): value is boolean;

Example:

import { isBoolean } from '@hemjs/notions';

isBoolean(false);
// => true
isBoolean(0);
// => false
isBoolean(null);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a boolean, otherwise false.

isClass

Determines whether a given value is a class.

Type:

function isClass<T = unknown>(value: unknown): value is Class<T>;

Example:

import { isClass } from '@hemjs/notions';

class Bar {}

isClass(Bar);
// => true
isClass(new Bar());
// => false
isClass(0);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a class, otherwise false.

isEmpty

Determines whether a given value is considered empty.

Type:

function isEmpty(value?: any): value is EmptyLike;

Empty Definitions:

• null: Returns true when a null value is given.
• undefined: Returns true when an undefined value is given.
• boolean: Returns true when the boolean value is false.
• integer: Returns true when an integer 0 value is given.
• float: Returns true when a float 0.0 value is given.
• string: Returns true when an empty string '' is given.
• space: Returns true when an string is given which contains only whitespace.
• array: Return true when an empty array ([]) or an array containing only empty values is given.
• object: Returns true when an empty object ({}) or an object with all properties being null, undefined, or empty strings is given.

Example:

import { isEmpty } from '@hemjs/notions';

// Arrays
isEmpty([]);
// => true
isEmpty([0, false, '', null, undefined]);
// => true
isEmpty([1, 'hello', { a: 1 }]);
// => false

// Objects
isEmpty({});
// => true
isEmpty({ a: null, b: undefined, c: '' });
// => true
isEmpty({ a: 1, b: 'hello' });
// => false

// Strings
isEmpty('');
// => true
isEmpty('  ');
// => true
isEmpty('hello');
// => false

// Other Values
isEmpty(null);
// => true
isEmpty(undefined);
// => true
isEmpty(false);
// => true
isEmpty(0);
// => true
isEmpty(0.0);
// => true
isEmpty(true);
// => false
isEmpty(1);
// => false
isEmpty('hello');
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is empty, otherwise false.

isFunction

Determines whether a given value is of type function.

Type:

function isFunction(value?: any): value is (...args: any[]) => any;

Example:

import { isFunction } from '@hemjs/notions';

isFunction(() => {});
// => true
isFunction(Math.random);
// => true
isFunction(0);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a function, otherwise false.

isNil

Determines whether a given value is nullish (null or undefined).

Type:

function isNil(value?: any): value is null | undefined;

Example:

import { isNil } from '@hemjs/notions';

isNil(null);
// => true
isNil(undefined);
// => true
isNil(0);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is nullish, otherwise false.

isNull

Determines whether a given value is exactly null.

Type:

function isNull(value?: any): value is null;

Example:

import { isNull } from '@hemjs/notions';

isNull(null);
// => true
isNull(undefined);
// => false
isNull(0);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is null, otherwise false.

isNumber

Determines whether a given value is of type number.

Type:

function isNumber(value?: any): value is number;

Example:

import { isNumber } from '@hemjs/notions';

isNumber(10);
// => true
isNumber(Math.PI);
// => true
isNumber('10');
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a number, otherwise false.

isObject

Determines whether a given value is of type object (excluding null).

Type:

function isObject(value?: any): value is object;

Example:

import { isObject } from '@hemjs/notions';

isObject({});
// => true
isObject([]);
// => true
isObject(null);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is an object (excluding null), otherwise false.

isPlainObject

Determines whether a given value is a plain object (i.e., an object without a custom prototype).

Type:

function isPlainObject(value?: any): value is object;

Example:

import { isPlainObject } from '@hemjs/notions';

isPlainObject({});
// => true
isPlainObject([]);
// => false
isPlainObject(Object.create(null));
// => true

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a plain object, otherwise false.

isString

Determines whether a given value is of type string.

Type:

function isString(value?: any): value is string;

Example:

import { isString } from '@hemjs/notions';

isString('hello');
// => true
isString(Symbol('hello'));
// => false
isString(10);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a string, otherwise false.

isSymbol

Determines whether a given value is of type symbol.

Type:

function isSymbol(value?: any): value is symbol;

Example:

import { isSymbol } from '@hemjs/notions';

isSymbol(Symbol('hello'));
// => true
isString('hello');
// => false
isSymbol(10);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is a symbol, otherwise false.

isUndefined

Determines whether a given value is undefined.

Type:

function isUndefined(value?: any): value is undefined;

Example:

import { isUndefined } from '@hemjs/notions';

isUndefined(undefined);
// => true
isUndefined(null);
// => false
isUndefined(0);
// => false

Parameters:

• value: The value to be checked. Can be any data type.

Returns:

true if value is undefined, otherwise false.

Object

omit

Creates a new object with specific properties omitted from a source object.

Type:

function omit<T extends Record<string, any>, K extends keyof T>(
  obj: T,
  exclusions: K[],
): Omit<T, K>;

Example:

import { omit } from '@hemjs/notions';

const person = { name: 'Alice', age: 30, city: 'Nairobi' };
const publicInfo = omit(person, ['age']);
console.log(publicInfo); // Output: { name: 'Alice', city: 'Nairobi' }

Parameters:

• obj: The source object from which properties will be copied.
• exclusions: An array of property keys to exclude from the new object.

Returns:

A new object containing all properties from obj except those listed in exclusions.

Notes:

• Uses a for...in loop and direct property assignments for optimal performance.

pick

Creates a new object containing only the specified properties from a source object.

Type:

function pick<T extends Record<string, any>, K extends keyof T>(
  obj: T,
  inclusions: K[],
): Pick<T, K>;

Example:

import { pick } from '@hemjs/notions';

const person = { name: 'Alice', age: 30, city: 'Nairobi' };
const nameAndAge = pick(person, ['name', 'age']);
console.log(nameAndAge); // Output: { name: 'Alice', age: 30 }

Parameters:

• obj: The source object from which properties will be copied.
• inclusions: An array of property keys to include in the new object.

Returns:

A new object containing only the properties listed in inclusions from obj.

Notes:

• Uses a for...in loop and direct property assignments for optimal performance.

License

This project is licensed under the MIT license.

See LICENSE for more information.