Passing in arguments via the command line is an extremely basic programming task, and a necessity for anyone trying to write a simple Command-Line Interface (CLI). In Node.js, as in C and many related environments, all command-line arguments received by the shell are given to the process in an array called argv (short for ‘argument values’).
Node.js exposes this array for every running process in the form of process.argv – let’s take a look at an example. Make a file called test.js and add this line:
console.log(process.argv);
Now save it, and try the following in your shell:
There you have it – an array containing any arguments you passed in. Notice the first two elements – node and the path to your script. These will always be present – even if your program takes no arguments of its own, your script’s interpreter and path are still considered arguments to the shell you’re using.
Where everyday CLI arguments are concerned, you’ll want to skip the first two. Now try this in test.js
var myArgs = process.argv.slice(2);
console.log('myArgs: ', myArgs);This yields:
$ node argv.js one two three four five myArgs: [ 'one', 'two', 'three', 'four', 'five' ]