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isPersian

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Detect whether a string is Persian (Farsi) or contains Persian characters, and normalize Arabic-script characters to their Persian equivalents. Use when validating Persian input, deciding whether to apply Persian-specific formatting, or auto-converting Arabic characters typed on an Arabic keyboard. Triggers on requests mentioning isPersian, hasPersian, isFarsi, autoArabicToPersian, Farsi detection, Persian validation, or "is this text Persian".

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Source SKILL.md: https://github.com/persian-tools/persian-tools/blob/HEAD/skills/isPersian/SKILL.md

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isPersian — Persian/Farsi script detection and normalization

import {
  isPersian,
  hasPersian,
  isFarsi,
  hasFarsi,
  autoArabicToPersian,
} from "@persian-tools/persian-tools";
// CommonJS
const {
  isPersian,
  hasPersian,
  isFarsi,
  hasFarsi,
  autoArabicToPersian,
} = require("@persian-tools/persian-tools");

Public exports

isPersian(str: string, isComplex?: boolean, trimPattern?: RegExp): boolean
isFarsi(str: string, isComplex?: boolean, trimPattern?: RegExp): boolean   // alias of isPersian
hasPersian(str: string, isComplex?: boolean): boolean
hasFarsi(str: string, isComplex?: boolean): boolean                         // alias of hasPersian
autoArabicToPersian(value: string): string

// Constants
TRIM_REGEX: RegExp        // /["'-+()؟\s.]/g — characters trimmed from input before checking
// Plus exports re-routed from ./farsiChars (faText, faComplexText)

isPersian vs hasPersian

  • isPersian(str) — all of str (after trimming common punctuation) is Persian.
  • hasPersian(str) — str contains at least one Persian character.
isPersian("سلام دنیا");          // true
isPersian("Hello سلام");         // false (English chars present)
hasPersian("Hello سلام");        // true (some Persian present)
hasPersian("Hello");             // false

The isComplex flag

isPersian("سلام؟ ۱۲۳", true);   // true — complex mode accepts Persian digits & extended punctuation
isPersian("سلام؟ ۱۲۳");          // false — default mode is strict letter-only

Use isComplex: true when validating free-form Persian text that legitimately contains digits, exclamation/question marks, or other common Persian punctuation. Default (false) is for "is this a pure Persian word" checks.

The trimPattern parameter

Before testing, characters matching trimPattern are stripped. Default is TRIM_REGEX = /["'-+()؟\s.]/g. Override when your input has additional separators that should be tolerated:

isPersian("سلام / دنیا", false, /[/\s]/g);   // true — strip slashes and whitespace

autoArabicToPersian — Arabic-keyboard normalization

The most common Persian-input bug: users type on Arabic keyboards and produce text with ي (Arabic ya, U+064A) and ك (Arabic kaf, U+0643) instead of the Persian ی (U+06CC) and ک (U+06A9). These render identically but compare as different bytes.

import { autoArabicToPersian } from "@persian-tools/persian-tools";

autoArabicToPersian("علي بن أبي طالب");   // "علی بن أبی طالب"
autoArabicToPersian("كتاب");               // "کتاب"

// Idempotent — already-Persian text passes through
autoArabicToPersian("علی");                // "علی"

Always run autoArabicToPersian on user input before any equality check, regex match, or Set/Map lookup keyed by Persian strings. Several validators in this library (e.g. moneyWordsToNumber) do this automatically when their autoConvertArabicCharsToPersian: true option is on (which is the default).

Common edge cases

InputisPersian(...)
""passes the regex against empty string → false (no characters to match)
"سلام"true
"سلام " (trailing whitespace)true — whitespace is trimmed
"123"false — digits aren't Persian letters
"۱۲۳" (default mode)false — strict mode treats digits as non-letters
"۱۲۳" (complex mode)true — complex mode includes Persian digits
"السلام" (Arabic text)false — Arabic-only chars like ل are still in the Arabic block; isPersian rejects strings that contain Persian-specific exclusions

Common pitfalls

  • Don't confuse isPersian with isArabic. Both scripts share most letters; the discriminator is the Persian-specific letters (پ چ ژ گ and the Persian code-point versions of ya/kaf). If you need "is this Arabic", load the isArabic skill.
  • isPersian("علي") returns false despite looking Persian — the ي is the Arabic code point. Normalize with autoArabicToPersian first when you want to accept either.
  • Whitespace-only strings: empty string and pure whitespace both return false. If you want a clear validation message, check .trim().length > 0 separately.

References

  • Sibling: src/modules/isArabic/ (for the Arabic-script counterpart)
  • Tests: test/isPersian.spec.ts
  • Domain background: .agents/persian-text-expert/SKILL.md