process.argv

Learn CLI arguments with process.argv.

What is process.argv?

process.argv is an array that holds the command-line arguments. When Node.js runs a script it fills this array automatically. The first two elements are fixed; the rest are the arguments the user passed.

Specifically: argv[0] holds the path to the Node.js executable and argv[1] holds the path to the script being run. argv[2] and beyond are the arguments the user typed on the command line. For example, with node app.js hello the value of argv[2] is hello. This lets you pass data into your program from outside.

Reading values from argv

You read the first user argument with process.argv[2]. But if the user gives no argument, this value is undefined. You can replace it with a default using the || operator.

For example, writing const name = process.argv[2] || "Node"; uses the argument if the user gave one, otherwise "Node". This pattern is very common in CLI tools: the program does not crash on missing arguments, it runs with a sensible default. For more complex cases you can loop over the process.argv array and extract options shaped like --flag.

Exercise Read the first argument and print it

Read the first user argument with process.argv[2]. If it is missing, use "Node" as a default with ||. Print it with console.log.

Show example solution

const name = process.argv[2] || "Node";
console.log(name);

Test yourself

At which index is the first user argument in process.argv?
```
process.argv
```
- argv[1]
- argv[0]
- argv[2]
- argv[3]
Show answer

argv[2] — argv[0] and argv[1] are Node and the script path; the first user argument is argv[2].

Read the first argument

const name = process.argv[____] || "Node";

Show answer

const name = process.argv[2] || "Node";

Match each index to its role

argv[0]

Node path
argv[1]

Script path
argv[2]

First user argument
argv[3]

Second user argument

Next lesson: process.env

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