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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]

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]

• javascript
• arrays
• node.js
• arguments

Share Improve this question Follow edited Nov 16, 2015 at 9:25 Chris asked Nov 16, 2015 at 8:55 ChrisChris 94433 gold badges1212 silver badges2323 bronze badges 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 Commented Nov 16, 2015 at 9:01

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2 Answers 2

Sorted by: Reset to default 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' ]

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.

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