Develop Reference

How do I get Guard to automatically compile my Coffeescript file? Says it is but it's not

I have the following Guardfile
coffeescript_options = {
input: 'src/js',
output: 'www/js',
patterns: [%r{^src/js/(.+\.(?:coffee|coffee\.md|litcoffee|js))$}]
}
guard 'coffeescript', :input => 'src/js', :output => 'www/js' do
coffeescript_options[:patterns].each { |pattern| watch(pattern) }
end
# guard 'coffeescript', :input => 'src/js', :output => 'www/js'
I save the src/js/tf.coffee file and it logs this
02:46:50 - INFO - Compile src/js/tf.coffee
02:46:50 - INFO - 02:46:50 AM Successfully generated
←]2;[CoffeeScript results] Successfully generated
However, I can't find the file anywhere.
$ find . -name tf.js
$ ls www/js
app.js
It works for HAML. This is a Ruby app, not Rails. (PhoneGap actually.) I tried the commented line in the Guardfile and it did not recognize changes to the file. I'm on Windows 8.1. I have Node v5.4.0 installed. I can run coffee -o www/js src/js/tf.coffee and it generates the JS file OK.
Docs: https://github.com/netzpirat/guard-coffeescript

Oops, I had to change the guard line to
guard 'coffeescript', coffeescript_options do
I had changed it to try to simplify it, but forgot to change it back. Still not sure why the commented out line doesn't work though.

Error Compiling node.js v0.10.31 for armv7

When trying to compile Node.js v0.10.31 (and v0.10.30) on Ubuntu 14.04 for use on Raspberry pi (running ARM). I'm using the following compiler flags:
export AR=arm-linux-gnueabihf-ar
export CC=arm-linux-gnueabihf-gcc
export CXX=arm-linux-gnueabihf-g++
export LINK=arm-linux-gnueabihf-g++
However I get the following error:
make -C out BUILDTYPE=Release V=1
make[1]: Entering directory `/home/ubuntu/node/out'
arm-linux-gnueabihf-g++ -pthread -rdynamic -Wl,--whole-archive /home/ubuntu/node/out/Release/libopenssl.a -Wl,--no-whole-archive -Wl,--whole-archive /home/ubuntu/node/out/Release/obj.target/deps/v8/tools/gyp/libv8_base.a -Wl,--no-whole-archive -pthread -o /home/ubuntu/node/out/Release/node -Wl,--start-group /home/ubuntu/node/out/Release/obj.target/node/src/fs_event_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/cares_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/handle_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/node.o /home/ubuntu/node/out/Release/obj.target/node/src/node_buffer.o /home/ubuntu/node/out/Release/obj.target/node/src/node_constants.o /home/ubuntu/node/out/Release/obj.target/node/src/node_extensions.o /home/ubuntu/node/out/Release/obj.target/node/src/node_file.o /home/ubuntu/node/out/Release/obj.target/node/src/node_http_parser.o /home/ubuntu/node/out/Release/obj.target/node/src/node_javascript.o /home/ubuntu/node/out/Release/obj.target/node/src/node_main.o /home/ubuntu/node/out/Release/obj.target/node/src/node_os.o /home/ubuntu/node/out/Release/obj.target/node/src/node_script.o /home/ubuntu/node/out/Release/obj.target/node/src/node_stat_watcher.o /home/ubuntu/node/out/Release/obj.target/node/src/node_string.o /home/ubuntu/node/out/Release/obj.target/node/src/node_zlib.o /home/ubuntu/node/out/Release/obj.target/node/src/pipe_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/signal_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/string_bytes.o /home/ubuntu/node/out/Release/obj.target/node/src/stream_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/slab_allocator.o /home/ubuntu/node/out/Release/obj.target/node/src/tcp_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/timer_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/tty_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/process_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/v8_typed_array.o /home/ubuntu/node/out/Release/obj.target/node/src/udp_wrap.o /home/ubuntu/node/out/Release/obj.target/node/src/node_crypto.o /home/ubuntu/node/out/Release/obj.target/deps/openssl/libopenssl.a /home/ubuntu/node/out/Release/obj.target/deps/zlib/libchrome_zlib.a /home/ubuntu/node/out/Release/obj.target/deps/http_parser/libhttp_parser.a /home/ubuntu/node/out/Release/obj.target/deps/cares/libcares.a /home/ubuntu/node/out/Release/obj.target/deps/uv/libuv.a /home/ubuntu/node/out/Release/obj.target/deps/v8/tools/gyp/libv8_base.a /home/ubuntu/node/out/Release/obj.target/deps/v8/tools/gyp/libv8_nosnapshot.a -Wl,--end-group -lm -ldl -lrt
/home/ubuntu/node/out/Release/libopenssl.a(armcap.o): In function `OPENSSL_cpuid_setup':
armcap.c:(.text.startup+0x0): multiple definition of `OPENSSL_cpuid_setup'
/home/ubuntu/node/out/Release/libopenssl.a(cryptlib.o):cryptlib.c:(.text+0x360): first defined here
/home/ubuntu/node/out/Release/libopenssl.a(armcap.o): In function `OPENSSL_rdtsc':
armcap.c:(.text+0x36): undefined reference to `_armv7_tick'
/home/ubuntu/node/out/Release/libopenssl.a(armcap.o): In function `OPENSSL_cpuid_setup':
armcap.c:(.text.startup+0xe0): undefined reference to `_armv7_tick'
armcap.c:(.text.startup+0x10c): undefined reference to `_armv7_neon_probe'
collect2: error: ld returned 1 exit status
make[1]: *** [/home/ubuntu/node/out/Release/node] Error 1
make[1]: Leaving directory `/home/ubuntu/node/out'
make: *** [node] Error 2
Any ideas how to solve this error? Thank you!

I recently installed Node on a Raspberry Pi (do not use apt-get, even on Raspbian. If you can move to Raspbian, as far as I know Ubuntu doesn't like ARM). Try this:
$ cd /home/pi/node/ #or any directory you want
$ wget http://node-arm.herokuapp.com/node_latest_armhf.deb
$ sudo dpkg -i node_latest_armhf.deb
If you try to open the REPL ($ node) and this gives you an error, it's probably because it can't find the executable find. In that case this following command made it work for me:
$ hash -r

I used the following to install node.js on RPi.
Install Node on the Raspberry Pi in 5 minutes
The problem I found was that the latest node.js distribution (v0.10.31) did not include the precompiled version for the RPi. I had to go the last distribution that contained the precompiled node.js for the RPi (v0.10.28). Here is the link to the distribution repository:
http://nodejs.org/dist/

Bulk fix missing semicolons that JSHints finds in project

I have a project of 100+ javascript files each with 1-5 missing semicolons according to JSHint (as a result multiple people working on the project with different conventions).
I'd like to bulk fix everything as it's not practical to fix each individually. I've found this: https://github.com/jshint/fixmyjs but I don't see a way only fix semicolons without 'fixing' other things (tabs -> spaces, for example).
Does anyone know of way to do this? I'm comfortable with the possibility that it might cause breakage/introduce bugs. I've look over the errors and they look pretty routine.

I really hope you like this as a solution. Be vary careful that you verify with jshint again after you've fixed the issues. And out of curiosity, how did you manage to get so many broken javascript files?
#!/bin/sh
function fixFile {
for i in `jshint $1 | grep -i "Missing semicolon" \
| sed -e 's/\([^0-9]*\)\([0-9]*\)\(.*$\)/\2/'`;
do
sed -i $1 -e $i's/\(\s*\)$/;/'
done
}
fixFile $1
The above uses jshint to produce some error lines, greps them for the missing semicolon errors only, extracts the line number of each error, then seds the file in place on that line to remove any trailing whitespace and replace it with a semicolon.
The file...
var a = 5, c = 4
function helloWorld() {
if (this == doesntmakesense)
console.log('hello' + 'world');
}
console.log(a+c);
console.log('finished')
...becomes...
var a = 5, c = 4;
function helloWorld() {
if (this == doesntmakesense)
console.log('hello' + 'world');
}
console.log(a+c);
console.log('finished');
Where petty semantic errors are ignored, and only semicolons treated.
I'd save the bash script as something like fixFile.sh and then run find . -name "*.js" -exec ./fixFile.sh {} \;
But please commit beforehand. All commands are run at your own risk ;)

There is a safer way of adding missing semicolons than using regular expressions. Use the following steps to configure fixmyjs to only fix semicolons as originally asked by Evan:
Install fixmyjs
npm install fixmyjs -g
Create a fixmyjs config file fixmyjs-config with the following content
{ "asi": false }
Run fixmyjs
fixmyjs --config [fixmyjs-config] --legacy yourfile.js
Reference: https://github.com/jshint/fixmyjs/issues/86

Google Closure JS Linter has a program that comes with it, able to correct some of the more regular violations such as this one I believe, it's named fixjsstyle (python btw)

How to pass argument to Mongo Script

I've been using mongo and script files like this:
$ mongo getSimilar.js
I would like to pass an argument to the file:
$ mongo getSimilar.js apples
And then in the script file pick up the argument passed in.
var arg = $1;
print(arg);

Use --eval and use shell scripting to modify the command passed in.
mongo --eval "print('apples');"
Or make global variables (credit to Tad Marshall):
$ cat addthem.js
printjson( param1 + param2 );
$ ./mongo --nodb --quiet --eval "var param1=7, param2=8" addthem.js
15

You can't do that, but you could put them in another script and load that first:
// vars.js
msg = "apples";
and getSimilar.js was:
print(msg);
Then:
$ mongo vars.js getSimilar.js
MongoDB shell version: blah
connecting to: test
loading file: vars.js
loading file: getSimilar.js
apples
Not quite as convenient, though.

Set a shell var:
password='bladiebla'
Create js script:
cat <<EOT > mongo-create-user.js
print('drop user admin');
db.dropUser('admin');
db.createUser({
user: 'admin',
pwd: '${password}',
roles: [ 'readWrite']
});
EOT
Pass script to mongo:
mongo mongo-create-user.js

I used a shell script to pipe a mongo command to mongo. In the mongo command I used an arg I passed to the shell script (i.e. i used $1):
#!/bin/sh
objId=$1
EVAL="db.account.find({\"_id\" : \"$objId\"})"
echo $EVAL | mongo localhost:27718/balance_mgmt --quiet

2022 update:
when using mongosh you can read the execution arguments from process.argv
mongosh script.js param1 param2
// process.argv will be [.... , 'param1', param2']
the tricky bit is that mongosh will try to execute the parameters (e.g. param1 and param2) as additional scripts, but this can be prevented by ending the script using quit(). (TBH, I'm not sure it's by design / intended / documented)

I wrote a small utility to solve the problem for myself. With the mongoexec utility, you would be able to run the command ./getSimilar.js apples by adding the following to the beginning of your script:
#!/usr/bin/mongoexec --quiet
Within the script, you can then access the arguments as args[0].
https://github.com/pveierland/mongoexec

I solved this problem, by using the javascript bundler parcel: https://parceljs.org/
With this, one can use node environment variables in a script like:
var collection = process.env.COLLECTION;
when building with parcel, the env var gets inlined:
parcel build ./src/index.js --no-source-maps
The only downside is, that you have to rebuild the script every time you want to change the env vars. But since parcel is really fast, this is not really a problem imho.

execute some code and then go into interactive node

Is there a way to execute some code (in a file or from a string, doesn't really matter) before dropping into interactive mode in node.js?
For example, if I create a script __preamble__.js which contains:
console.log("preamble executed! poor guy!");
and a user types node __preamble__.js they get this output:
preamble executed! poor guy!
> [interactive mode]

Really old question but...
I was looking for something similar, I believe, and found out this.
You can open the REPL (typing node on your terminal) and then load a file.
Like this: .load ./script.js.
Press enter and the file content will be executed. Now everything created (object, variable, function) in your script will be available.
For example:
// script.js
var y = {
name: 'obj',
status: true
};
var x = setInterval(function () {
console.log('As time goes by...');
}, 5000);
On the REPL:
//REPL
.load ./script.js
Now you type on the REPL and interact with the "living code".
You can console.log(y) or clearInterval(x);
It will be a bit odd, cause "As time goes by..." keep showing up every five seconds (or so).
But it will work!

You can start a new repl in your Node software pretty easily:
var repl = require("repl");
var r = repl.start("node> ");
r.context.pause = pauseHTTP;
r.context.resume = resumeHTTP;
From within the REPL you can then call pause() or resume() and execute the functions pauseHTTP() and resumeHTTP() directly. Just assign whatever you want to expose to the REPL's context member.

This can be achieved with the current version of NodeJS (5.9.1):
$ node -i -e "console.log('A message')"
The -e flag evaluates the string and the -i flag begins the interactive mode.
You can read more in the referenced pull request

node -r allows you to require a module when REPL starts up. NODE_PATH sets the module search path. So you can run something like this on your command line:
NODE_PATH=. node -r myscript.js
This should put you in a REPL with your script loaded.

I've recently started a project to create an advanced interactive shell for Node and associated languages like CoffeeScript. One of the features is loading a file or string in the context of the interpreter at startup which takes into account the loaded language.
http://danielgtaylor.github.com/nesh/
Examples:
# Load a string (Javascript)
nesh -e 'var hello = function (name) { return "Hello, " + name; };'
# Load a string (CoffeeScript)
nesh -c -e 'hello = (name) -> "Hello, #{name}"'
# Load a file (Javascript)
nesh -e hello.js
# Load a file (CoffeeScript)
nesh -c -e hello.coffee
Then in the interpreter you can access the hello function.

Edit: Ignore this. #jaywalking101's answer is much better. Do that instead.
If you're running from inside a Bash shell (Linux, OS X, Cygwin), then
cat __preamble__.js - | node -i
will work. This also spews lots of noise from evaluating each line of preamble.js, but afterwords you land in an interactive shell in the context you want.
(The '-' to 'cat' just specifies "use standard input".)

Similar answer to #slacktracer, but if you are fine using global in your script, you can simply require it instead of (learning and) using .load.
Example lib.js:
global.x = 123;
Example node session:
$ node
> require('./lib')
{}
> x
123
As a nice side-effect, you don't even have to do the var x = require('x'); 0 dance, as module.exports remains an empty object and thus the require result will not fill up your screen with the module's content.

Vorpal.js was built to do just this. It provides an API for building an interactive CLI in the context of your application.
It includes plugins, and one of these is Vorpal-REPL. This lets you type repl and this will drop you into a REPL within the context of your application.
Example to implement:
var vorpal = require('vorpal')();
var repl = require('vorpal-repl');
vorpal.use(repl).show();
// Now you do your custom code...
// If you want to automatically jump
// into REPl mode, just do this:
vorpal.exec('repl');
That's all!
Disclaimer: I wrote Vorpal.

There isn't a way do this natively. You can either enter the node interactive shell node or run a script you have node myScrpt.js. #sarnold is right, in that if you want that for your app, you will need to make it yourself, and using the repl toolkit is helpful for that kind of thing

nit-tool lets you load a node module into the repl interactive and have access to inner module environment (join context) for development purposes
npm install nit-tool -g

First I tried
$ node --interactive foo.js
but it just runs foo.js, with no REPL.
If you're using export and import in your js, run npm init -y, then tell node that you're using modules with the "type": "module", line -
{
"name": "neomem",
"version": "1.0.0",
"description": "",
"type": "module",
"main": "home.js",
"keywords": [],
"author": "",
"license": "ISC"
}
Then you can run node and import a file with dynamic import -
$ node
Welcome to Node.js v18.1.0.
Type ".help" for more information.
> home = await import('./home.js')
[Module: null prototype] {
get: [AsyncFunction: get],
start: [AsyncFunction: start]
}
> home.get('hello')
Kind of a roundabout way of doing it - having a command line switch would be nice...