String Class Extension for determining if a string has unicode characters or not.

String.prototype.containsUnicode.js

/**
 * @method containsUnicode
 * @extends {String}
 * 
 * @returns {Boolean} - True iff <String> contains one or more Unicode Characters
 */
String.prototype.containsUnicode = function () {
  return this.split('').reduce((a,x)=> a || x.charCodeAt(0) > 255, false)
}

Usage:

let happyEN = "happy";
let happyZH = "快乐";

console.log("happyEN contains Unicode Chars:", happyEN.containsUnicode()); // "happyEN contains Unicode Chars: false"
console.log("happyZH contains Unicode Chars:", happyZH.containsUnicode()); // "happyZH contains Unicode Chars: true"