@fekit/utils

Lightweight TypeScript utility library for frontend projects.

@fekit/utils provides small helpers for type checks, data cleanup, enum-tree lookup, date formatting, validation, display formatting, object diffing, number padding, and runtime environment detection.

For AI and LLM usage, read AI_CONTEXT.md. It contains the complete API map, usage guidance, edge cases, and examples.

Install

yarn add @fekit/utils

npm i @fekit/utils

Import

import { idate, format, validate, isString, deepcopy } from '@fekit/utils';

All public APIs are exported from the package root.

API Areas

Type Checks

import {
  getType,
  isFunction,
  isObject,
  isArray,
  isUndefined,
  isNull,
  isString,
  isBoolean,
  isNumber,
  isDate,
  isDateString,
  isElement,
  isNodeList,
  isEmpty,
  isBase64,
  isBlob,
  isJsonString,
  isArrayString,
  isObjectString,
  isEncoded,
  hasOwnProp,
} from '@fekit/utils';

isEmpty(''); // true
isEmpty(0); // false
isDateString('2025-02-31'); // false
hasOwnProp({ name: 'fekit' }, 'name'); // true

Data Helpers

import { deepcopy, cleandata, findByJson, filterJson, dataToEnum, getFileType, findEnumName } from '@fekit/utils';

cleandata({ name: '  Alice  ', empty: '', tags: ['x', ''] });
// { name: 'Alice', tags: ['x'] }

getFileType('/files/report.pdf?download=1');
// 'pdf'

Date Helpers

import { idate } from '@fekit/utils';

idate('2026-06-25').format('YYYY-MM-DD'); // '2026-06-25'
idate('20260817').format('YYYY-MM-DD'); // '2026-08-17'
idate(20260817).format('YYYY-MM-DD'); // '2026-08-17'
idate('2026年8月17日').format('YYYY-MM-DD'); // '2026-08-17'
idate('17/08/2026', { format: 'DD/MM/YYYY' }).format('YYYY-MM-DD'); // '2026-08-17'
idate('2026-06-25').update({ d: 1 }).format('YYYY-MM-DD'); // '2026-06-26'
idate(Date.now()).humanized(); // relative time string

idate() returns an IDate instance with .format(), .update(), .humanized(), and .calendar().

Validation

import { validate, validateEmail, validateNumber, verify } from '@fekit/utils';

validate('email', '[email protected]'); // true
validateEmail('[email protected]'); // true
validateNumber('12.5'); // true

verify(form, data, route) validates form-field configs and returns an array of error objects.

Formatting

import { format } from '@fekit/utils';

format.toPhoneNumber('13800138000'); // '138-0013-8000'
format.toThousands(1234567.89); // '1,234,567.89'
format.toFillZero(8, 3); // '008'

Diff And Fill

import { diff, fill } from '@fekit/utils';

diff({ a: 1 }, { a: '1' }); // []
diff({ a: 1 }, { a: '1' }, true); // [{ field: 'a', lhs: 1, rhs: '1', path: ['a'] }]
fill({ a: 1 }, { a: 2, b: 3 }); // { a: 1, b: null }

Number Helpers

import { numfill } from '@fekit/utils';

numfill(7); // '07'
numfill(-7); // '-07'

Environment Detection

import { env, useEnvInfo, createEnvInfo } from '@fekit/utils';

env.mobile; // dynamically computed boolean
useEnvInfo(); // full runtime environment state
createEnvInfo({ userAgent: 'Mozilla/5.0 ...', hasWindow: true, hasDocument: true });

AI-Friendly Files

• AI_CONTEXT.md: complete machine-readable API guide.
• llms.txt: curated LLM entry file that can be published at a website root as /llms.txt.

Notes

• The package has no runtime dependencies.
• format is an object of formatter methods, not a function.
• diff() uses loose string comparison by default. Pass true or { strict: true } for strict comparison.
• idate() accepts valid Date, date strings (YYYY-MM-DD, YYYY/MM/DD, ISO, YYYYMMDD, Chinese 2026年8月17日), 8-digit YYYYMMDD numbers, undefined for now, and 10-13 digit timestamps. Day-first DD/MM/YYYY requires { format: 'DD/MM/YYYY' }.