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Iranian and Arabic input often arrives with three different numeral systems mixed together. These functions move between them and provide an autoConvertDigitsToEN helper that normalizes any input to English digits.

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The three systems

SystemSampleUnicode range
English (Latin)0123456789U+0030 – U+0039
Persian (Farsi)۰۱۲۳۴۵۶۷۸۹U+06F0 – U+06F9
Arabic-Indic٠١٢٣٤٥٦٧٨٩U+0660 – U+0669
These are disjoint ranges — Persian digits ≠ Arabic-Indic digits despite casual users using the names interchangeably.

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Converters

import {
	digitsEnToFa,
	digitsEnToAr,
	digitsFaToEn,
	digitsFaToAr,
	digitsArToEn,
	digitsArToFa,
	autoConvertDigitsToEN,
} from "@persian-tools/persian-tools";

digitsEnToFa("Card 1234"); // "Card ۱۲۳۴"
digitsEnToFa(2025); // "۲۰۲۵"
digitsFaToEn("شماره ۰۹۱۲"); // "شماره 0912"
digitsArToFa("٧٨٩"); // "۷۸۹"

// When input may have BOTH Persian and Arabic digits — most real user input
autoConvertDigitsToEN("تماس ۰۹۱۲ یا ٠٩١٣"); // "تماس 0912 یا 0913"
autoConvertDigitsToEN is the right default when ingesting unknown user input (form field, copy-paste, OCR).

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Input rules and errors

  • digitsEnToFa / digitsEnToAr accept string | number. Anything else throws TypeError("PersianTools: digitsEnToFa - The input must be string or number") (and similarly for digitsEnToAr).
  • digitsFaToEn, digitsFaToAr, digitsArToEn, digitsArToFa accept string. Anything else throws TypeError("PersianTools: <fn> - The input must be string").
  • autoConvertDigitsToEN passes falsy input through as-is (no throw).

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Exported constants

import { enNums, faNums, arNums, enDigitsRegex, faDigitsRegex, arDigitsRegex } from "@persian-tools/persian-tools";

enNums; // ["0", "1", ..., "9"]
faNums; // ["۰", "۱", ..., "۹"]
arNums; // ["٠", "١", ..., "٩"]

enDigitsRegex; // /[0-9]/g
faDigitsRegex; // /[۰۱۲۳۴۵۶۷۸۹]/g
arDigitsRegex; // /[٠١٢٣٤٥٦٧٨٩]/g
Use these when building larger custom regexes — don’t re-declare the character classes inline.

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Types

import type { DigitsConverter } from "@persian-tools/persian-tools";

type DigitsConverter<I = string, O = string> = (value: I) => O;

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Pitfalls

  • The strict converters throw on null / undefined / wrong types — they do NOT gracefully return "". Wrap in try/catch or guard upstream.
  • digitsFaToEn leaves Arabic digits untouched. Use autoConvertDigitsToEN for mixed input.
  • Hand-rolling with String.fromCharCode math is fragile — the Persian and Arabic ranges sit at different offsets. Use these functions.

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Source

src/modules/digits/ (converters/, digits.constants.ts) · Tests: test/digits.spec.ts