'use strict'; var stripAnsi = require('strip-ansi'); var codePointAt = require('code-point-at'); var isFullwidthCodePoint = require('is-fullwidth-code-point'); // https://github.com/nodejs/io.js/blob/cff7300a578be1b10001f2d967aaedc88aee6402/lib/readline.js#L1345 module.exports = function (str) { if (typeof str !== 'string' || str.length === 0) { return 0; } var width = 0; str = stripAnsi(str); for (var i = 0; i < str.length; i++) { var code = codePointAt(str, i); // ignore control characters if (code <= 0x1f || (code >= 0x7f && code <= 0x9f)) { continue; } // surrogates if (code >= 0x10000) { i++; } if (isFullwidthCodePoint(code)) { width += 2; } else { width++; } } return width; };