is-japanese

An npm library checks if the content only contains Japanese characters. Returns true if a given string only contains Japanese characters, false if it contains non-Japanese characters.

Install

npm i is-japanese

Usage

var isJapanese = require("is-japanese");
console.log(isJapanese("東京")) // true
console.log(isJapanese("東京Japan")) // false

This library tolerates Hiragana, Katakana, Kanji, common half and full Japanese punctuations, common Japanese symbols, and number 0-9.

The general standard is based on modern Japanese phrasings we read in online paltforms like Yahoo Japan. More examples from Yahoo News inculde:

var isJapanese = require("is-japanese");
console.log(isJapanese("新型コロナ対策は「評価する」が25.2％だったのに対して「評価しない」は71.5％。")) // true
console.log(isJapanese("朝日で63％、共同では83％、NHKは68.7％に達している。")) // false, 'NHK' are not Japanese characters

Benchmark

Device: MacBook Pro (Retina, 13-inch, Early 2015)

Node: v12.13.1

isJapanese("今夜の月は綺麗ですね") x 7,530,755 ops/sec ±21.34% (37 runs sampled)
isJapanese("ss今夜の月は綺麗ですね") x 20,593,769 ops/sec ±19.35% (34 runs sampled)
isJapanese("今夜の月は綺麗ですねss") x 10,912,107 ops/sec ±58.65% (33 runs sampled)
isJapanese(chars1000) true x 45,771 ops/sec ±24.30% (30 runs sampled)
isJapanese(chars1001) false x 232,222 ops/sec ±30.26% (26 runs sampled)

Ackowledgement

This project is heavily based on the is-chinese library.

License

MIT