I am using a function from one file, in another file, and calling it there. This is causing the function to run twice at the same time when run from the command line, but not when I run it in VSCode.
Here is an example:
// fileOne
async function task() {
console.log('Hello')
}
module.exports = { task }
// fileTwo
const fileOne = require('./fileOne');
fileOne.task();
Output when ran in VSCode:
Hello
Output when ran in Command Line:
Hello
Hello
I'm not sure why this is happening... No I am not calling it in fileOne by accident because then it would also run twice in VSCode.
Thanks.
If your fileOne and fileTwo look exactly as in your problem statement, i.e.:
fileOne.js:
async function task() {
console.log('Hello')
}
module.exports = { task }
fileTwo.js:
const fileOne = require('./fileOne');
fileOne.task();
the output is 1 single 'Hello' when run in the following ways:
in Command Prompt
node fileTwo.js
in Windows PowerShell
node .\fileTwo.js
in Linux Bash Terminal
$ nodejs fileTwo.js
The same applies if you run the script having both files within 1 file (as you mention in the comments).
There were some cases where Node.js would print the output twice, but those were different scenarios.
You can try running just the fileTwo.js separately, but as already mentioned, it worked well also under a common file (e.g. your my_program_here.js in case it is just a combination of fileOne.js and fileTwo.js).
const fileOne = require('./fileOne');
This is based on the './' in different command lines.
With jest I'm not able to test commander module functions that result in process exit.
For example, if I pass the --help option or an invalid parameter like -x (see below) process.exit or process.stdout.write are not called as they should looking at the commander sources.
import {Command} from "commander";
let mockExit: jest.SpyInstance;
let mockStdout: jest.SpyInstance;
beforeAll(() => {
mockExit = jest.spyOn(process, "exit").mockImplementation();
mockStdout = jest.spyOn(process.stdout, "write").mockImplementation();
});
afterAll(() => {
mockExit.mockRestore();
mockStdout.mockRestore();
});
test("Ask for help", () => {
// Setup
const save = JSON.parse(JSON.stringify(process.argv));
process.argv = ["--help"]; // Same setting it to "-x"
const program = new Command();
program
.option("-v, --verbose [level]", "verbose level")
.parse(process.argv);
expect(mockExit).toBeCalled();
// expect(mockStdout).toBeCalled();
// Cleanup
process.argv = save;
});
What is strange is that, from the behavior of other tests, process.argv is not restored after this one.
Tests are in typescript and passed through ts-jest.
Any ideas?
Thanks!
I suggest you use .exitOverride(), which is the approach Commander uses in its own tests. This means early "termination" is via a throw rather than exit.
https://github.com/tj/commander.js#override-exit-handling
The first problem though (from comments) is the arguments. Commander expects the parse arguments follow the conventions of node with argv[0] is the application and argv[1] is the script being run, with user parameters after that.
So instead of:
argsToParse = ["--help"];
something like:
argsToParse = ['node", "dummy.js", "--help"];
(No need to modify process.argv as such.)
Within a nodejs script I have the following code which makes the call synchronously and returns the stdout from the shell script I am calling:
var sh = require('shelljs');
... some code
var output = sh.exec('./someshellscript.sh', {silent:true}).stdout;
console.log(output);
... some more code (that shouldnt run until the script is complete)
I can also run the following script which will instead return the stderr:
var sh = require('shelljs');
... some code
var output = sh.exec('./someshellscript.sh', {silent:true}).stderr;
console.log(output);
... some more code (that shouldnt run until the script is complete)
However I want to receive both stdout and stderr in a sync call. Its probably something pretty obvious I am missing herebut I cant work it out.
I think you used to be able run the following command in previous versions but this just returns undefined now:
var sh = require('shelljs');
... some code
var output = sh.exec('./someshellscript.sh', {silent:true}).output;
console.log(output);
... some more code (that shouldnt run until the script is complete)
Relevant software versions are:
Ubuntu: 14.04.3 LTS
node: 4.4.4
npm: 2.15.1
shelljs: 0.7.0
Any help appreciated thanks.
From the README for the method exec(command [, options] [, callback])
Executes the given command synchronously, unless otherwise specified. [...], returns an object of the form { code:..., stdout:... , stderr:... }).
Therefore
const { stdout, stderr, code } = sh.exec('./someshellscript.sh', { silent: true })
I am still in the process of learning node and have come across this issue. In the following situation, and using a silly example (the full code can not be placed here), when I run in the terminal node index.js somethinghere, the code does not execute. I realise that event and context have no bearing in this example, but they do in the code I am currently writing.
Is this because I am doing exports.imageRs?
How would I get it to run on the command line by passing in arguments?
Note that the original code is to be run on both aws lambda and from the command line.
file index.js
exports.imageRs = function (event, context) {
console.log(process.argv);
}
In the example you have shown Node will define exports.imageRs function but it won't execute it.
The fix is something along these lines:
exports.imageRs = function (event, context) {
console.log(process.argv);
};
if (!module.parent) {
exports.imageRs();
}
!module.parent check prevents the code inside from executing when your module is required from other modules, which is probably what you want.
$ node index.js somethinghere
[ '/path/to/node',
'/path/to/index.js',
'somethinghere' ]
$ node
> require('./index')
{ imageRs: [Function] }
I would like to be able to open Vim from node.js program running in the terminal, create some content, save and exit Vim, and then grab the contents of the file.
I'm trying to do something like this:
filename = '/tmp/tmpfile-' + process.pid
editor = process.env['EDITOR'] ? 'vi'
spawn editor, [filename], (err, stdout, stderr) ->
text = fs.readFileSync filename
console.log text
However, when this runs, it just hangs the terminal.
I've also tried it with exec and got the same result.
Update:
This is complicated by the fact that this process is launched from a command typed at a prompt with readline running. I completely extracted the relevant parts of my latest version out to a file. Here is it in its entirety:
{spawn} = require 'child_process'
fs = require 'fs'
tty = require 'tty'
rl = require 'readline'
cli = rl.createInterface process.stdin, process.stdout, null
cli.prompt()
filename = '/tmp/tmpfile-' + process.pid
proc = spawn 'vim', [filename]
#cli.pause()
process.stdin.resume()
indata = (c) ->
proc.stdin.write c
process.stdin.on 'data', indata
proc.stdout.on 'data', (c) ->
process.stdout.write c
proc.on 'exit', () ->
tty.setRawMode false
process.stdin.removeListener 'data', indata
# Grab content from the temporary file and display it
text = fs.readFile filename, (err, data) ->
throw err if err?
console.log data.toString()
# Try to resume readline prompt
cli.prompt()
The way it works as show above, is that it shows a prompt for a couple of seconds, and then launches in to Vim, but the TTY is messed up. I can edit, and save the file, and the contents are printed correctly. There is a bunch of junk printed to terminal on exit as well, and Readline functionality is broken afterward (no Up/Down arrow, no Tab completion).
If I uncomment the cli.pause() line, then the TTY is OK in Vim, but I'm stuck in insert mode, and the Esc key doesn't work. If I hit Ctrl-C it quits the child and parent process.
You can inherit stdio from the main process.
const child_process = require('child_process')
var editor = process.env.EDITOR || 'vi';
var child = child_process.spawn(editor, ['/tmp/somefile.txt'], {
stdio: 'inherit'
});
child.on('exit', function (e, code) {
console.log("finished");
});
More options here: http://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options
Update: My answer applied at the time it was created, but for modern versions of Node, look at this other answer.
First off, your usage of spawn isn't correct. Here are the docs. http://nodejs.org/docs/latest/api/child_processes.html#child_process.spawn
Your sample code makes it seem like you expect vim to automatically pop up and take over the terminal, but it won't. The important thing to remember is that even though you may spawn a process, it is up to you to make sure that the data from the process makes it through to your terminal for display.
In this case, you need to take data from stdin and send it to vim, and you need to take data output by vim and set it to your terminal, otherwise you won't see anything. You also need to set the tty into raw mode, otherwise node will intercept some of the key sequences, so vim will not behave properly.
Next, don't do readFileSync. If you come upon a case where you think you need to use a sync method, then chances are, you are doing something wrong.
Here's a quick example I put together. I can't vouch for it working in every single case, but it should cover most cases.
var tty = require('tty');
var child_process = require('child_process');
var fs = require('fs');
function spawnVim(file, cb) {
var vim = child_process.spawn( 'vim', [file])
function indata(c) {
vim.stdin.write(c);
}
function outdata(c) {
process.stdout.write(c);
}
process.stdin.resume();
process.stdin.on('data', indata);
vim.stdout.on('data', outdata);
tty.setRawMode(true);
vim.on('exit', function(code) {
tty.setRawMode(false);
process.stdin.pause();
process.stdin.removeListener('data', indata);
vim.stdout.removeListener('data', outdata);
cb(code);
});
}
var filename = '/tmp/somefile.txt';
spawnVim(filename, function(code) {
if (code == 0) {
fs.readFile(filename, function(err, data) {
if (!err) {
console.log(data.toString());
}
});
}
});
Update
I seeee. I don't think readline is as compatible with all of this as you would like unfortunately. The issue is that when you createInterface, node kind of assumes that it will have full control over that stream from that point forward. When we redirect that data to vim, readline is still there processing keypresses, but vim is also doing the same thing.
The only way around this that I see is to manually disable everything from the cli interface before you start vim.
Just before you spawn the process, we need to close the interface, and unfortunately manually remove the keypress listener because, at least at the moment, node does not remove it automatically.
process.stdin.removeAllListeners 'keypress'
cli.close()
tty.setRawMode true
Then in the process 'exit' callback, you will need to call createInterface again.
I tried to do something like this using Node's repl library - https://nodejs.org/api/repl.html - but nothing worked. I tried launching vscode and TextEdit, but on the Mac there didn't seem to be a way to wait for those programs to close. Using execSync with vim, nano, and micro all acted strangely or hung the terminal.
Finally I switched to using the readline library using the example given here https://nodejs.org/api/readline.html#readline_example_tiny_cli - and it worked using micro, e.g.
import { execSync } from 'child_process'
...
case 'edit':
const cmd = `micro foo.txt`
const result = execSync(cmd).toString()
console.log({ result })
break
It switches to micro in a Scratch buffer - hit ctrl-q when done, and it returns the buffer contents in result.