How to pass .json file name as argument to command line in node.js

Question

I run app.js with command node app.js

It executes const inputData = require('./input.json');

Is it possible pass file name as argument to const inputData = require('./file.json'); from command line? I mean:

node app.js file.json

I am totally new to this trickery, have no theoretical point. From where I should start? Many thanks for all possible help.

Much obliged,

you have process.argv to access cmdline arguments stackoverflow.com/a/4351548/3410584. Then simply require with the good index — ValLeNain
– ValLeNain, Commented Nov 12, 2017 at 17:12

Pedro Rodrigues · Accepted Answer · 2017-11-12 17:31:36Z

5

You can use the process.argv to access arguments, and fs.readFile or fs.readFileSync to read file content.

const fs = require('fs');

// Non-blocking example with fs.readFile
const fileNames = process.argv.splice(2);

fileNames.forEach(fileName => {
    fs.readFile(fileName, 'utf-8', (error, data) => {
        if (error) throw error;
        console.log(fileName, data);
  });
});

// Blocking example with fs.readFileSync
const fileName = fileNames[0];
console.log(fileName, fs.readFileSync(fileName, 'utf-8'));

answered Nov 12, 2017 at 17:31

Pedro Rodrigues

1,69615 silver badges23 bronze badges

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

1 Comment

o.O Over a year ago

Why I can't put console.log(fileName, fs.readFileSync(fileName, 'utf-8')); into const?

Collectives™ on Stack Overflow

How to pass .json file name as argument to command line in node.js

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related