how to debug node.js program from log message - node.js

Question

I am new to server side programming and got some error message when tried to boost a node.js program(egg.js framework)
It is not that kind of bug that I made because of my certain line of code such as "undefined var xx ", I just don't know how to debug it from these messages
0 info it worked if it ends with ok
1 verbose cli [ 'C:\\node\\node.exe',
1 verbose cli 'C:\\nvm\\nvm\\node_global\\node_modules\\npm\\bin\\npm-cli.js',
1 verbose cli 'start' ]
2 info using npm#5.6.0
3 info using node#v8.10.0
4 verbose run-script [ 'prestart', 'start', 'poststart' ]
5 info lifecycle blog-server#1.0.0~prestart: blog-server#1.0.0
6 info lifecycle blog-server#1.0.0~start: blog-server#1.0.0
7 verbose lifecycle blog-server#1.0.0~start: unsafe-perm in lifecycle true
8 verbose lifecycle blog-server#1.0.0~start: PATH: C:\nvm\nvm\node_global\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin;C:\Users\z\Desktop\Allen's-Blog\blog-server\node_modules\.bin;C:\Users\z\bin;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\local\bin;C:\Program Files\Git\usr\bin;C:\Program Files\Git\usr\bin;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\Users\z\bin;C:\Program Files\ImageMagick-7.0.6-Q16;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0;C:\Python27;C:\WINDOWS\System32\OpenSSH;C:\Program Files\Java\jdk1.8.0_171\bin;C:\Program Files\Java\jdk1.8.0_171\jre\bin;D:\Software\gradle\bin;C:\nvm\nvm;C:\node;C:\nvm\nvm\node_global;C:\Program Files\Git\cmd;C:\Program Files\PuTTY;C:\Program Files\TortoiseSVN\bin;C:\Program Files\MongoDB\Server\4.0\bin;C:\Program Files (x86)\SMLNJ\bin;C:\Users\z\AppData\Local\Programs\Python\Python35\Scripts;C:\Users\z\AppData\Local\Programs\Python\Python35;C:\Ruby24-x64\bin;C:\Users\z\AppData\Local\Microsoft\WindowsApps;node_global;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\nvm\nvm;C:\node;D:\Software\fiddle\Fiddler;D:\projects\Microsoft VS Code\bin;C:\Program Files\Git\usr\bin\vendor_perl;C:\Program Files\Git\usr\bin\core_perl
9 verbose lifecycle blog-server#1.0.0~start: CWD: C:\Users\z\Desktop\Allen's-Blog\blog-server
10 silly lifecycle blog-server#1.0.0~start: Args: [ '/d /s /c',
10 silly lifecycle 'egg-scripts start --daemon --title=egg-server-blog-server' ]
11 silly lifecycle blog-server#1.0.0~start: Returned: code: 1 signal: null
12 info lifecycle blog-server#1.0.0~start: Failed to exec start script
13 verbose stack Error: blog-server#1.0.0 start: `egg-scripts start --daemon --title=egg-server-blog-server`
13 verbose stack Exit status 1
13 verbose stack at EventEmitter.<anonymous> (C:\nvm\nvm\node_global\node_modules\npm\node_modules\npm-lifecycle\index.js:285:16)
13 verbose stack at emitTwo (events.js:126:13)
13 verbose stack at EventEmitter.emit (events.js:214:7)
13 verbose stack at ChildProcess.<anonymous> (C:\nvm\nvm\node_global\node_modules\npm\node_modules\npm-lifecycle\lib\spawn.js:55:14)
13 verbose stack at emitTwo (events.js:126:13)
13 verbose stack at ChildProcess.emit (events.js:214:7)
13 verbose stack at maybeClose (internal/child_process.js:925:16)
13 verbose stack at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)
14 verbose pkgid blog-server#1.0.0
15 verbose cwd C:\Users\z\Desktop\Allen's-Blog\blog-server
16 verbose Windows_NT 10.0.17134
17 verbose argv "C:\\node\\node.exe" "C:\\nvm\\nvm\\node_global\\node_modules\\npm\\bin\\npm-cli.js" "start"
18 verbose node v8.10.0
19 verbose npm v5.6.0
20 error code ELIFECYCLE
21 error errno 1
22 error blog-server#1.0.0 start: `egg-scripts start --daemon --title=egg-server-blog-server`
22 error Exit status 1
23 error Failed at the blog-server#1.0.0 start script.
23 error This is probably not a problem with npm. There is likely additional logging output above.
24 verbose exit [ 1, true ]

Answer 1

Use this command : console.log( <The variable you want to debug> ); when ever you want to debug something,
Exp :
var arr = [1,2,3,4,5];
for (let i in arr){
console.log(i);
}
There are plenty of other debugging tool and IDEs that can also help you (I recommend using VSCode, it's easy to use and have decent functionalities).