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                const str = '𠮷野家で𩸽'; // Surrogate pairs in UTF-16 strings

console.log('ES5: Use length (not correct)', str.length); // 7
console.log('ES2015: Use Spread Operator (not work on', [...str].length); // 1

function strlenEs5(str) {
  return str.length - (str.match(/[\uD800-\uDBFF][\uDC00-\uDFFF]/g) || []).length;
console.log('ES5: Use length with regexp', strlenEs5(str)); // 5

function strlenEs2015(str) {
  let chars = [];
  for (let c of str) {
  return chars.length;
console.log('ES2015: Use for...of statement', strlenEs2015(str)); // 5

function strlen(str) {
  let ary = Array.from(str);
  return ary.length;
console.log('ES2015: Use Array.from() method', strlen(str)); // 5