test-repo/src/utilities/get-string-width.js

import emojiRegex from "emoji-regex";
import {
  // @ts-expect-error -- Private
  _isFullwidth as isFullwidth,
  // @ts-expect-error -- Private
  _isWide as isWide,
} from "get-east-asian-width";
import { isNarrowEmojiCharacter } from "narrow-emojis";

const notAsciiRegex = /[^\x20-\x7F]/;
// Exclude [`Spacing Mark`](https://www.compart.com/en/unicode/category/Mc) because spacing marks contribute horizontal width.
const zeroWidthMarkRegex = /[\p{Nonspacing_Mark}\p{Enclosing_Mark}]/u;

// Similar to https://github.com/sindresorhus/string-width
// We don't strip ansi, always treat ambiguous width characters as having narrow width.
/**
 * @param {string} text
 * @returns {number}
 */
function getStringWidth(text) {
  if (!text) {
    return 0;
  }

  // shortcut to avoid needless string `RegExp`s, replacements, and allocations
  if (!notAsciiRegex.test(text)) {
    return text.length;
  }

  let width = 0;
  text = text.replace(emojiRegex(), (character) => {
    width += isNarrowEmojiCharacter(character) ? 1 : 2;
    return "";
  });

  // Use `Intl.Segmenter` when we drop support for Node.js v14
  // https://github.com/prettier/prettier/pull/14793#discussion_r1185840038
  // https://github.com/sindresorhus/string-width/pull/47
  for (const character of text) {
    const codePoint = character.codePointAt(0);

    // Ignore control characters
    if (codePoint <= 0x1f || (codePoint >= 0x7f && codePoint <= 0x9f)) {
      continue;
    }

    // Ignore zero-width marks, including combining marks and variation selectors
    if (zeroWidthMarkRegex.test(character)) {
      continue;
    }

    width += isFullwidth(codePoint) || isWide(codePoint) ? 2 : 1;
  }

  return width;
}

export default getStringWidth;