'use strict';
  var numberIsNan = require('number-is-nan');
  
  module.exports = function (x) {
  	if (numberIsNan(x)) {
  		return false;
  	}
  
  	// https://github.com/nodejs/io.js/blob/cff7300a578be1b10001f2d967aaedc88aee6402/lib/readline.js#L1369
  
  	// code points are derived from:
  	// http://www.unix.org/Public/UNIDATA/EastAsianWidth.txt
  	if (x >= 0x1100 && (
  		x <= 0x115f ||  // Hangul Jamo
  		0x2329 === x || // LEFT-POINTING ANGLE BRACKET
  		0x232a === x || // RIGHT-POINTING ANGLE BRACKET
  		// CJK Radicals Supplement .. Enclosed CJK Letters and Months
  		(0x2e80 <= x && x <= 0x3247 && x !== 0x303f) ||
  		// Enclosed CJK Letters and Months .. CJK Unified Ideographs Extension A
  		0x3250 <= x && x <= 0x4dbf ||
  		// CJK Unified Ideographs .. Yi Radicals
  		0x4e00 <= x && x <= 0xa4c6 ||
  		// Hangul Jamo Extended-A
  		0xa960 <= x && x <= 0xa97c ||
  		// Hangul Syllables
  		0xac00 <= x && x <= 0xd7a3 ||
  		// CJK Compatibility Ideographs
  		0xf900 <= x && x <= 0xfaff ||
  		// Vertical Forms
  		0xfe10 <= x && x <= 0xfe19 ||
  		// CJK Compatibility Forms .. Small Form Variants
  		0xfe30 <= x && x <= 0xfe6b ||
  		// Halfwidth and Fullwidth Forms
  		0xff01 <= x && x <= 0xff60 ||
  		0xffe0 <= x && x <= 0xffe6 ||
  		// Kana Supplement
  		0x1b000 <= x && x <= 0x1b001 ||
  		// Enclosed Ideographic Supplement
  		0x1f200 <= x && x <= 0x1f251 ||
  		// CJK Unified Ideographs Extension B .. Tertiary Ideographic Plane
  		0x20000 <= x && x <= 0x3fffd)) {
  		return true;
  	}
  
  	return false;
  }