[Node.js] Pass command line arguments to node.js

Command line arguments are often used to modify the behavior of an application or specify needed parameters for operation. In this lesson, you will learn how to access the command line arguments passed to your node.js application as well as different strategies for evaluating and accessing them.

To catch what arguement user passed in from command line, we can use 'process.argv'.

If we log out:

// server.js

console.log(process.argv)

Then we run the command:

node server.js foo bar soo

In the console, it log out this:

[ '/usr/local/bin/node',
  '/Users/zhentianwan/Documents/Programming/Node/nol/server',
  'foo',
  'bar',
  'soo' ]

Here the 'foo bar soo' are meaningless, but in the real case, the argv user pass in might be something we need, but the order might be differet, for example, sometime you do: 

npm i ramda --save

Somtime you might:

npm i --save ramda

The order of command can be different.

To make sure what user has pass in, we can do:

if (process.argv.indexOf('foo') != -1) { console.log('Yeah! We are going to foo!'); }