Function visualWidth

src/tui/utils.js:4–21

(ch)

// It is CJK-aware and surrogate-pair safe for simple emojis, but full terminal
// wcwidth compliance and ZWJ grapheme clusters are intentionally out of scope.
function visualWidth(ch) {
  const cp = ch.codePointAt(0);
  if (!cp) return 0;
  if (cp >= 0x1100 && (
    cp <= 0x115F ||                    // Hangul Jamo
    (cp >= 0x2E80 && cp <= 0xA4CF) ||  // CJK Radicals, Kangxi, Ideographic Description, CJK Symbols, Hiragana, Katakana, Bopomofo, etc.
    (cp >= 0xA960 && cp <= 0xA97C) ||  // Hangul Jamo Extended-A
    (cp >= 0xAC00 && cp <= 0xD7AF) ||  // Hangul Syllables
    (cp >= 0xF900 && cp <= 0xFAFF) ||  // CJK Compatibility Ideographs
    (cp >= 0xFE10 && cp <= 0xFE19) ||  // Vertical Forms
    (cp >= 0xFE30 && cp <= 0xFE6F) ||  // CJK Compatibility Forms
    (cp >= 0xFF01 && cp <= 0xFF60) ||  // Fullwidth Forms
    (cp >= 0xFFE0 && cp <= 0xFFE6) ||  // Fullwidth Signs
    (cp >= 0x20000 && cp <= 0x2FFFF) || // CJK Unified Ideographs Extension B-F
    (cp >= 0x30000 && cp <= 0x3FFFF)   // CJK Unified Ideographs Extension G-H
  )) return 2;
  return 1;
}

function visualLength(str) {
  let len = 0;