How can we write a shell script using NodeJs - javascript

I need to read CSV file, process the file via REST API call and then write the output in another CSV file. The requirement is strictly shell script using NodeJs.
I am using Windows platform

You could add a shebang to your .js file and make it executable.
#!/usr/bin/env node
console.log('...')
Alternatively you make a wrapper bash script and execute whatever you want
#!/usr/bin/env bash
node whatever.js

If you are on linux, start your script with the following line:
#!/usr/bin/env node
This would indicate that node interpreter should be used to execute this file.
Then make the file executable:
chmod +x your_script.js
At this point it should be possible to run script as any regular executable, e.g:
./your_script.js

Related

Execute multiple terser commands (compression/mangling) inside a .bat file

Terser is a free tool for compressing and/or mangling javascript files.
As far as I have understood, the tool relies on node.js, so that is a pre-req for running Terser in the first place.
This will execute the terser command on a single file:
terser input.js -c -m -o output.js
This is fine for some files that aren't updated frequently, but if you have a large set of Javascript files in your project that are updated instantly, you would appreciate something more dynamic.
I was thinking about including each file command inside a .bat file and execute that as one file, but I cannot get that to work: I tried placing these between the ECHO AND PAUSE commands in the bat file but it doesn't work well unfortunately.
As far as I have seen, the documentation covers just running terser as CLI
Is there a way to "move" the command lines from the CLI environment to the .bat file?
I encountered the same problem today as I was trying to use "terser" in batch files for the first time (instead of uglify-es I used precedently)
After each "terser" command the execution of the batch file stops
After adding a pipe | pause at the end of each terser command, my batch file runs as usual and executes the next commands.

Node js 'console' error in cmd

I want to use the node.js on the windows. so I install node but I can't execute a .js file. That is my source code. And I atteched the error screen.
helloworld.js
console.log("Hello, World!")
This error is happening because your script is not executed with nodejs but with Microsoft jscript.
The command you wrote "node node.js" is executing the file ode.js instead of the nodejs in your system in the same way you can execute cmd by typing cmd instead of cmd.exe.
To fix that you need to do one of those :
rename the file to something other than node
move the file named node in a subfolder (i.e. src/node.js)
associate .js file with nodejs instead of microsoft jscript

How to run TypeScript program on Windows?

If we write a Typescript program then how should we run it on Windows?
We already know how to run Javascript (.js) from a command line on Windows:
C:\Users\Harikesh>cscript MyScriptFile.js
What is the equivalent for TypeScript (.ts) files?
You can compile the Typescript down to Javascript, and then run it from a command line with Node.js, or in a web browser:
1) Download and install Node.js.
2) Open a Windows command prompt and run:
npm install -g typescript
3) Navigate to the directory where your typescript file is in, and type:
tsc yourtypescriptfile.ts
4a) Run the resulting JavaScript file with Node.js:
node yourtypescriptfile.js
-or-
4b) Make an HTML file (in the same directory) that includes yourtypescriptfile.js using <source></source> tags:
<script src="yourtypescriptfile.js"></script>
5) Open your HTML file in a web browser.
Help from:
http://javascript.info/tutorial/adding-script-html
If we write a typescript program then how should we run it on window platform?
Using NodeJS : https://nodejs.org/en/
Same as JavaScript to be exact.

node js local enviroment setup

i m trying to create local enviroment for learning node.js
i m following the link below
http://www.tutorialspoint.com/nodejs/nodejs_environment_setup.htm
i downloaded Windows Installer (.msi) on my computer and create a file named main.js
console.log("main.js");
and i double clicked node.exe
on command prompt i m getting unexpected identifier exeption what s wrong?
After answers i also tried followings
i created a new folder on my desktop and accessed to it. i got same error.
i also used Windows Powershell
Don't put your files into the nodejs-folder!
Create a new folder (e.g. on your Desktop) and put main.js in it
Start a command prompt (hit Windows+R and type cmd.exe)
Navigate to your newly created folder using cd
Run main.js by typing node main.js
If you enter node and press enter, you start something like a console. You can directly write JavaScript commands, e.g.
C:\Temp>node
> console.log('Hello World');
Hello World
undefined
>
If you started node and then enter node main.js, node will try to understand this command as JavaScript which is obviously not JavaScript. What you want to do is to enter node main.js directly:
C:\Temp>node main.js
Hello World
See the difference: In the first example you start node and then enter some JavaScript commands and in the second example you start node but with the parameter main.js which tells node not to start this "console" but to load this file and run it.
You are expected to type node filename.js from your command line shell.
You've run node (presumably by double clicking its icon) and are trying to type node filename.js from the node REPL instead of your shell.
Open Zsh, Bash, Windows Powershell or similar and run it from there.
Access your file from a command Prompt like node yourFile. Also make sure you have installed node properly.To check that just type node -v, it should give you the current node version. If all these things are done then check for errors in server.js, which is main.js in your case.

How can I beautify JavaScript code using Command Line?

I am writing a batch script in order to beautify JavaScript code. It needs to work on both Windows and Linux.
How can I beautify JavaScript code using the command line tools?
First, pick your favorite Javascript based Pretty Print/Beautifier. I prefer the one at http://jsbeautifier.org/, because it's what I found first. Downloads its file https://github.com/beautify-web/js-beautify/blob/master/js/lib/beautify.js
Second, download and install The Mozilla group's Java based Javascript engine, Rhino. "Install" is a little bit misleading; Download the zip file, extract everything, place js.jar in your Java classpath (or Library/Java/Extensions on OS X). You can then run scripts with an invocation similar to this
java -cp js.jar org.mozilla.javascript.tools.shell.Main name-of-script.js
Use the Pretty Print/Beautifier from step 1 to write a small shell script that will read in your javascript file and run it through the Pretty Print/Beautifier from step one. For example
//original code
(function() { ... js_beautify code ... }());
//new code
print(global.js_beautify(readFile(arguments[0])));
Rhino gives javascript a few extra useful functions that don't necessarily make sense in a browser context, but do in a console context. The function print does what you'd expect, and prints out a string. The function readFile accepts a file path string as an argument and returns the contents of that file.
You'd invoke the above something like
java -cp js.jar org.mozilla.javascript.tools.shell.Main beautify.js file-to-pp.js
You can mix and match Java and Javascript in your Rhino run scripts, so if you know a little Java it shouldn't be too hard to get this running with text-streams as well.
UPDATE April 2014:
The beautifier has been rewritten since I answered this in 2010. There is now a python module in there, an npm Package for nodejs, and the jar file is gone. Please read the project page on github.com.
Python style:
$ pip install jsbeautifier
NPM style:
$ npm -g install js-beautify
to use it (this will return the beatified js file on the terminal, the main file remains unchanged):
$ js-beautify file.js
To make the changes take effect on the file, you should use this command:
$ js-beautify -r file.js
Original answer
Adding to Answer of #Alan Storm
the command line beautifier based on http://jsbeautifier.org/ has gotten a bit easier to use, because it is now (alternatively) based on the V8 javascript engine (c++ code) instead of rhino (java-based JS engine, packaged as "js.jar"). So you can use V8 instead of rhino.
How to use:
download jsbeautifier.org zip file from
http://github.com/einars/js-beautify/zipball/master
(this is a download URL linked to a zip file such as http://download.github.com/einars-js-beautify-10384df.zip)
old (no longer works, jar file is gone)
java -jar js.jar name-of-script.js
new (alternative)
install/compile v8 lib FROM svn, see v8/README.txt in above-mentioned zip file
./jsbeautify somefile.js
-has slightly different command line options than the rhino version,
-and works great in Eclipse when configured as an "External Tool"
If you're using nodejs then try uglify-js
On Linux or Mac, assuming you already have nodejs installed, you can install uglify with:
sudo npm install -g uglify-js
And then get the options:
uglifyjs -h
So if I have a source file foo.js which looks like this:
// foo.js -- minified
function foo(bar,baz){console.log("something something");return true;}
I can beautify it like so:
uglifyjs foo.js --beautify --output cutefoo.js
uglify uses spaces for indentation by default so if I want to convert the 4-space-indentation to tabs I can run it through unexpand which Ubuntu 12.04 comes with:
unexpand --tabs=4 cutefoo.js > cuterfoo.js
Or you can do it all in one go:
uglifyjs foo.js --beautify | unexpand --tabs=4 > cutestfoo.js
You can find out more about unexpand here
so after all this I wind up with a file that looks like so:
function foo(bar, baz) {
console.log("something something");
return true;
}
update 2016-06-07
It appears that the maintainer of uglify-js is now working on version 2 though installation is the same.
On Ubuntu LTS
$ sudo apt install jsbeautifier
$ js-beautify ugly.js > beautiful.js
For in place beautifying, any of the follwing commands:
$ js-beautify -r file.js
$ js-beautify --replace file.js
You have a few one liner choices. Use with npm or standalone with npx.
Semistandar
npx semistandard "js/**/*.js" --fix
Standard
npx standard "js/**/*.js" --fix
Prettier
npx prettier --single-quote --write --trailing-comma all "js/**/*.js"
In the console, you can use Artistic Style (a.k.a. AStyle) with --mode=java.
It works great and it's free, open-source and cross-platform (Linux, Mac OS X, Windows).
Use the modern JavaScript way:
Use Grunt in combination with the jsbeautifier plugin for Grunt
You can install everything easily into your dev environment using npm.
All you will need is set up a Gruntfile.js with the appropriate tasks, which can also involve file concatenation, lint, uglify, minify etc, and run the grunt command.
I'm not able to add a comment to the accepted answer so that's why you see a post that should have not existed in the first place.
Basically I also needed a javascript beautifier in a java code and to my surprise none is available as far as I could find. So I coded one myself entirely based on the accepted answer (it wraps the jsbeautifier.org beautifier .js script but is callable from java or the command line).
The code is located at https://github.com/belgampaul/JsBeautifier
I used rhino and beautifier.js
USAGE from console: java -jar jsbeautifier.jar script indentation
example: java -jar jsbeautifier.jar "function ff() {return;}" 2
USAGE from java code:
public static String jsBeautify(String jsCode, int indentSize)
You are welcome to extend the code. In my case I only needed the indentation so I could check the generated javascript while developing.
In the hope it'll save you some time in your project.
I've written an article explaining how to build a command-line JavaScript beautifier implemented in JavaScript in under 5 minutes. YMMV.
Download the latest stable Rhino and unpack it somewhere, e.g. ~/dev/javascript/rhino
Download beautify.js which is referenced from aforementioned jsbeautifier.org then copy it somewhere, e.g. ~/dev/javascript/bin/cli-beautifier.js
Add this at the end of beautify.js (using some additional top-level properties to JavaScript):
// Run the beautifier on the file passed as the first argument.
print( j23s_beautify( readFile( arguments[0] )));
Copy-paste the following code in an executable file, e.g. ~/dev/javascript/bin/jsbeautifier.sh:
#!/bin/sh
java -cp ~/dev/javascript/rhino/js.jar org.mozilla.javascript.tools.shell.Main ~/dev/web/javascript/bin/cli-beautifier.js $*
(optional) Add the folder with jsbeautifier.js to PATH or moving to some folder already there.
I believe when you asked about command line tool you just wanted to beautify all your js files in batch.
In this case Intellij IDEA (tested with 11.5) can do this.
You just need to select any of your project files and select "Code"->"Reformat code.." in main IDE menu. Then in the dialog select "all files in directory ..." and press "enter".
Just make sure you dedicated enough memory for the JVM.

Categories