javascriptstringindexofcjkcharat

Javascript indexOf/charAt not working for Japanese half-width Katakana

In my codebase I have this code, surprisingly it returns 1:

'ﾄｹﾞ'.indexOf('ｹ') // Returns 1

The character ｹ doesn't seem to appear in string ﾄｹﾞ.

I also tried to run this code:

'ﾄｹﾞ'.charAt(1)  // Returns `ｹ`

And to my surprise it returns ｹ.

Can you explain why the codes above return 1 and ｹ? Thank you!

Solution

  • Your string consists of three characters: ﾄ, ｹ and ﾞ. There is no dedicated halfwidth-ge character, you'll always use a regular halfwidth character and add the halfwidth voiced sound mark to it, which will be rendered as the combined glyph ｹﾞ.

    Note that there is a dedicated fullwidth ゲ KATAKANA LETTER GE U+30B2.