``` function utf8_decode(str_data) { var tmp_arr = [], i = 0, ac = 0, c1 = 0, c2 = 0, c3 = 0; str_data += ""; while (i < str_data.length) { c1 = str_data.charCodeAt(i); if (c1 < 128) { tmp_arr[ac++] = String.fromCharCode(c1); i++; } else if (c1 > 191 && c1 < 224) { c2 = str_data.charCodeAt(i + 1); tmp_arr[ac++] = String.fromCharCode(((c1 & 31) << 6) | (c2 & 63)); i += 2; } else { c2 = str_data.charCodeAt(i + 1); c3 = str_data.charCodeAt(i + 2); tmp_arr[ac++] = String.fromCharCode( ((c1 & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63) ); i += 3; } } return tmp_arr.join(""); } ```