Is it possible (feasible) to format (fold) Node.js terminal output JSON?

Question

I'm a frontend developer, and I'm unfamiliar with command line tools for Node.js

I currently use iTerm with zShell, but I can't find any resources online about folding console output (similar to how the Chrome console formats objects). I tried using fx but can't seem to pipe and utilize the Node output through the util.

node -e 'console.log({ a: { b: 2 } })';
node -e 'console.log(JSON.stringify({ a: { b: 2 } }, null, 2))';

For large network objects, it would be much more convenient to fold the nested layers. It would also be great to have syntax highlighting.

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Is there an easy way to debug Node.js console output JSON?

Am I missing fundamental CLI tools? I know this is a relatively open-ended question, but I think it would be a good resource for other people in my situation (I've spent ~3 hours researching with barely any improvement).

Thanks

Answer 1

The problem with the first line is that node command doesn't produce valid JSON string when you use console.log. You need to encode the object as JSON string yourself.

The second line correctly encodes the object as JSON string (using stringify):

node -e 'console.log(JSON.stringify({ a: { b: 2 } }, null, 2))'

To pipe the JSON string output of the node command you need to omit the semicolon ;. The semicolon in bash is used to separate commands. More information about what semicolon means in bash: docstore.mik.ua/orelly/unix3/upt/ch28_16.htm

This is how you can pipe the ouptut to fx:

node -e 'console.log(JSON.stringify({ a: { b: 2 } }, null, 2))' | fx

And this is how you would pipe th output to jq:

node -e 'console.log(JSON.stringify({ a: { b: 2 } }, null, 2))' | jq

fx will be probably more intuitive to use.
jq might come in handy if you need to deal with large outputs.

jq is a lightweight and flexible command-line JSON processor.

Here is some information on how to install it: stedolan.github.io/jq/download

And here is a tutorial on how to do some basic filtering with jq: stedolan.github.io/jq/tutorial

Answer 2

It's worth mentioning that Node.js can be debugged by listening to localhost:9229

In my case:

1. I went to chrome://inspect/#devices
2. Opened Node.js debugger
3. changed localhost:9229 to 127.0.0.1:9229 on 'Connections' panel ... this took a few hours to discover
4. made and ran a package.json command "debug": "node --inspect-brk ./node_modules/jest/bin/jest.js --config=jest.config.js --timeout=60000 --runInBand",
5. accepted debugging in the Node.js sources panel and console.log didn't work, but watching variables was convenient

Answer 3

View Logs with Google Chrome

1. Run your Node server with the --inspect flag

$ node --inspect server.js

2. Open a new tab in Google Chrome and go to chrome://inspect/#devices

3. Now click on inspect to view all logs with the browser console