there are always some lines not mangled #5

var _0x4651 = ['connection\x20closed', 'indexOf', 'splice', 'error', 'Server\x20error:', 'message', 'clear\x20connection', 'Server\x20closed', 'logError', 'start error\x0d\x0a', 'middleware\x20is\x20running\x20at\x20%s:%d', 'stop', 'middleware\x20has\x20been\x20closed', 'status', 'exports', '../adapter/mssql-access', '../tools/log', '../middleware/hl7parser', 'moment', '127.0.0.1', 'readFile', './ip.json', 'log', 'read error \x0d\x0a', 'parse', 'connection', 'got\x20a\x20new\x20connection\x20host:', 'remoteAddress', '\x20port\x20is:', 'remotePort', 'push', 'data', 'getSearchData', 'toString', 'from', 'queryPromise', 'queryPId', 'then', 'queryExchangePromise', 'queryWithParamsPromise', 'length', 'getReturnMsg', 'getEmptyReturnMsg', 'writeLog', 'search sccess \x0d\x0a', 'concat', 'write', 'catch', 'search error\x0d\x0a', 'search empty\x0d\x0a', 'close'];
(function (_0x4a1d85, _0x54af7f) {
var _0x485f74 = function (_0xbba3c1) {
while (--_0xbba3c1) {
_0x4a1d85'push';
}
};
_0x485f74(++_0x54af7f);
}(_0x4651, 0x1c2));
var _0x1465 = function (_0x3dd15e, _0x1f0015) {
_0x3dd15e = _0x3dd15e - 0x0;
var _0x231fd0 = _0x4651[_0x3dd15e];
return _0x231fd0;
};
'use strict';
const net = require('net');
const fs = require('fs');
const mssql = require(_0x1465('0x0'));
const log = require(_0x1465('0x1'));
const hl7Parser = require(_0x1465('0x2'));
const moment = require(_0x1465('0x3'));
const server = net'createServer';

every time I packed my code ,there are some lines not mangled,sometimes is 'fs' and 'net',and sometimes another lines,can anyone explain this?thanks