Run mongodb problem

  mongodb, question
mongod --dbpath /usr/local/var/mongodb
2018-07-03T10:50:12.444+0800 I CONTROL  [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'
 2018-07-03T10:50:12.457+0800 I CONTROL  [initandlisten] MongoDB starting : pid=44555 port=27017 dbpath=/usr/local/var/mongodb 64-bit host=huhaifengdeMacBook-Pro.local
 2018-07-03T10:50:12.457+0800 I CONTROL  [initandlisten] db version v4.0.0
 2018-07-03T10:50:12.457+0800 I CONTROL  [initandlisten] git version: 3b07af3d4f471ae89e8186d33bbb1d5259597d51
 2018-07-03T10:50:12.457+0800 I CONTROL  [initandlisten] allocator: system
 2018-07-03T10:50:12.458+0800 I CONTROL  [initandlisten] modules: none
 2018-07-03T10:50:12.458+0800 I CONTROL  [initandlisten] build environment:
 2018-07-03T10:50:12.458+0800 I CONTROL  [initandlisten]     distarch: x86_64
 2018-07-03T10:50:12.458+0800 I CONTROL  [initandlisten]     target_arch: x86_64
 2018-07-03T10:50:12.458+0800 I CONTROL  [initandlisten] options: { storage: { dbPath: "/usr/local/var/mongodb" } }
 2018-07-03T10:50:12.458+0800 I STORAGE  [initandlisten] Detected data files in /usr/local/var/mongodb created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
 2018-07-03T10:50:12.458+0800 I STORAGE  [initandlisten] wiredtiger_open config: create,cache_size=7680M,session_max=20000,eviction=(threads_min=4,  threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),  file_manager=(close_idle_time=100000),statistics_log=(wait=0),verbose=(recovery_progress),
 2018-07-03T10:50:13.065+0800 I STORAGE  [initandlisten] WiredTiger message [1530586213:65896][44555:0x7fffa9ffe380], txn-recover: Main recovery loop: starting at 10/5888
 2018-07-03T10:50:13.160+0800 I STORAGE  [initandlisten] WiredTiger message [1530586213:160125][44555:0x7fffa9ffe380], txn-recover: Recovering log 10 through 11
 2018-07-03T10:50:13.224+0800 I STORAGE  [initandlisten] WiredTiger message [1530586213:224134][44555:0x7fffa9ffe380], txn-recover: Recovering log 11 through 11
 2018-07-03T10:50:13.273+0800 I STORAGE  [initandlisten] WiredTiger message [1530586213:273601][44555:0x7fffa9ffe380], txn-recover: Set global recovery timestamp: 0
 2018-07-03T10:50:13.347+0800 I RECOVERY [initandlisten] WiredTiger recoveryTimestamp. Ts: Timestamp(0, 0)
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten]
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten]
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] ** WARNING: This server is bound to localhost.
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          Remote systems will be unable to connect to this server.
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          Start the server with --bind_ip <address> to specify which IP
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          addresses it should serve responses from, or with --bind_ip_all to
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          bind to all interfaces. If this behavior is desired, start the
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] **          server with --bind_ip 127.0.0.1 to disable this warning.
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten]
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten]
 2018-07-03T10:50:13.386+0800 I CONTROL  [initandlisten] ** WARNING: soft rlimits too low. Number of files is 256, should be at least 1000
 2018-07-03T10:50:13.427+0800 I FTDC     [initandlisten] Initializing full-time diagnostic data capture with directory '/usr/local/var/mongodb/diagnostic.data'
 2018-07-03T10:50:13.431+0800 I NETWORK  [initandlisten] waiting for connections on port 27017
const express = require('express')
 const mongoose = require('mongoose')
 //Link mongo
 const DB_URL = 'mongodb://localhost:27017/'
 mongoose.connect(DB_URL)
 mongoose.connection.on('connected', function(){
 console.log('mongo connect success!'  )
 })
 //new app
 const app = express()
 app.get('/', function (req, res) {
 res.send('<h1>Hello World1e23</h1>')
 })
 app.get('/data', function(req, res) {
 res.json({name: 'hhf12ees3', type: 'IT'})
 })
 app.listen(9093, function(){
 console.log('Node app start at port 9093')
 })

Report a problem [nodmon] appcrashed-waiting for filechanges before starting. …
How to solve

I have solved the problem and must have a database name to run.