Running JavaScript from the windows command prompt

Question

I wrote the following JavaScipt code which converts a binary number into a decimal number:

(function bin_dec(num) {
  var x = num;
  var result = 0;
  for (var i = 0; i < x.length; i++) {
    result += eval(x[x.length - i] * 2^i);
  }
  return result;
})()

I want to be able to run this code from the command-line. The filename is converter.js and I am running the command prompt window in the same directory as the file. I am trying to run this code using 01001100 as the function argument. Here are my attempts:

$ converter.js 01001100

and

$ converter.js -01001100

and

$ converter.js bin_dec(01001100)

But unfortunately, neither of these works. Can somebody please point out my mistake? Thanks in advance.

you have an IIFE ... num argument will always be undefined because of how you've written the IIFE ... that aside ... running javascript on the command line ... how do you propose this to work? do you get any errors when you do that? I'm guessing you are running linux, right — Jaromanda X
– Jaromanda X, Commented Jan 21, 2017 at 9:19
But.. have you any tool that parses and executes JS from the command line? Like NodeJS or similar? Besides that, you have an IIFE, so no function declaration is present (ie bin_dec is not accessible from outside). Plus you don't need eval. — Margaret Bloom
– Margaret Bloom, Commented Jan 21, 2017 at 9:22

GOTO 0 · Accepted Answer · 2017-01-21 09:22:17Z

12

1) Install Node.js if you haven't done so yet.

2) Change your converter.js file like this:

function bin_dec(num) {
  return parseInt(num, 2);
}

console.log(bin_dec(process.argv[2]));

3) Open a new command prompt in the folder where your script is and run

$ node converter.js 01001100

answered Jan 21, 2017 at 9:22

GOTO 0

48.8k25 gold badges140 silver badges165 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bob Stein Over a year ago

Node.js console.log() is surprisingly rich. Unpacks and colorizes objects. And Unicode works! The scary prompt during Node.js install about compiling C/C++ appears to be optional. Basic stuff works without checking that box. Wish I knew what is missing though...

Ibrahim · Accepted Answer · 2017-01-21 09:22:02Z

In nodejs, assuming that you already have it installed since you are trying to run javascript from cmd, you will have to refer to the process.argv array in order to get the arguments passed in the command line.

So your code will need to look like this:

(function bin_dec(num) {
  var x = num;
  var result = 0;
  for (var i = 0; i < x.length; i++) {
    result += eval(x[x.length - i] * 2^i);
  }
  return result;
})(process.argv[2])

Notice process.argv[2] that is passed to the function. That will make the first argument available as the num variable inside your function.

You may also add a console.log somewhere if you want to have messages displayed on the screen, since the return statement will not print messages.

Bassie · Accepted Answer · 2017-01-21 09:30:23Z

2

Assuming you are running on Windows, You can call it like this:

(function bin_dec() {
  var x = WScript.arguments(0);
  var result = 0;
  for (var i = 0; i < x.length; i++) {
    result += eval(x[x.length - i] * 2^i);
  }
  return result;
})()

Where all parameters passed into the function are stored in WScript.arguments.

However, this will not output the return value to the command prompt, so you may want to test it out with this .js file:

(function ShowAlert() {
  var x = WScript.arguments(0);
  WScript.ECho(x);
})()

See these links for more details:

MSDN - Arguments Property

SS64 - WScript Arguments

SS64 - VBScript Command line arguments

edited Jan 21, 2017 at 9:30

answered Jan 21, 2017 at 9:24

Bassie

10.5k10 gold badges88 silver badges190 bronze badges

Comments

Nikhilesh Shivarathri · Accepted Answer · 2017-01-21 09:36:08Z

You'll have to know that, few basic functions like console or return statements will not work in CLI.

If you're using windows, then use 'WScript.echo' which is similar to console.log and while executing the file make sure you do it this way like

Cscript.exe yourpath input_params for example Cscript.exe converter.js 01001100

So your code should be

(function bin_dec() {
    var x = WScript.arguments(0);
    var result = 0;
    for (var i = 0; i < x.length; i++) {
        result += eval(x[x.length - i] * 2^i);
    }
    WScript.echo(result);
})();

and to run it should be

Cscript.exe converter.js 01001100

hope this helps you! For more information on CLI methods visit the following link

https://msdn.microsoft.com/en-us/library/2795740w(v=vs.84).aspx

Collectives™ on Stack Overflow

Running JavaScript from the windows command prompt

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related