Getting Array as a raw command line argument

Question

I am trying to implement raw command line arguments in Node.js.

When I implement simple variables everything works

(node example.js variable)

But when I implement as an argument an array it doesn't work

(node example.js "['127.0.0.5', '127.0.0.3']" )

Full code:

if (process.argv.length <= 3) {
    console.log("Usage: " + __filename + " SOME_PARAM");
    process.exit(-1);
}

var variable = process.argv[2];
var array = process.argv[3];

console.log('Host: ' + variable);
console.log('array: ' + array);

Problem

Example of input of arguments ( node example.js variable "['127.0.0.5', '127.0.0.3']" )

How to pass the second argument ("['127.0.0.5', '127.0.0.3']") as an array rather than as a string (as it is now), so that later I might access array's n-th element (example array[0] = '127.0.0.5' )

SOLUTION

The input should be like ( '["127.0.0.5", "127.0.0.3"]' changing the quotes), and also we need to parse the argument as JSON.

if (process.argv.length <= 3) {
    console.log("Usage: " + __filename + " SOME_PARAM");
    process.exit(-1);
}

var variable = process.argv[2];
var array = JSON.parse(process.argv[4]);

console.log('Host: ' + variable);
console.log('array: ' + array);
console.log(array[1]

You can't "pass it as an array" but you can parse the argument to build your array. You get a string no matter what, it's up to you to convert it into an array. — Yabada
– Yabada, Commented Nov 16, 2015 at 9:01

Vaibhav Nigam · Accepted Answer · 2020-06-07 03:31:50Z

12

It's an old question, but if someone still looking for a simple solution, here it is.

Pass named arguments multiple times with same name.

node example.js --variable=127.0.0.5 --variable=127.0.0.3

Use minimist NPM package to extract args as:

const parseArgs = require('minimist');

const args = parseArgs(process.argv.slice(2));
console.log(args.variable);

Output:

[ '127.0.0.5', '127.0.0.3' ]

answered Jun 7, 2020 at 3:31

Vaibhav Nigam

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2 Comments

app4g Over a year ago

Tried to Edit the post but "edit queue are full' so I'll put it a a comment. You may need to add a -- for npm to recognise the command line variable. node example.js -- --variable=127.0.0.5 --variable=127.0.0.3

lowtechsun Over a year ago

For an array where you only need to pass the values I converted the whole thing to a comma separated string with implode and on the JS side then did a string.split(','), with that I was able to feed a Node script the values I got from a PHP array. I guess for a simple case this could be done..

Andrius · Accepted Answer · 2015-11-16 09:10:11Z

3

You won't be able to pass an array. What you have to do (and possibly are in the middle of doing) is passing something like an array converted to a JSON string.

And in the application, you would just do a JSON.parse() to get your array out of the string.

answered Nov 16, 2015 at 9:10

Andrius

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