Use node.js commandline argument as environment variable

Question

I call my node.js application with

node index.js a=5

I want to use the value '5' directly as an environment variable in my code like

const myNumber = process.env.a

(like stated here).

If I try the above, 'MyNumber' is undefinded on runtime.

Solution

• Linux:

a=5 node index.js

• Windows (Powershell):

    $env:a="5";node index.js

Answer 1

When doing node index.js a=5, a=5 is an argument for node, as index.js is.

If you want to pass an environment variable, you must specify it before node command : a=5 node index.js.

The node process.env is populated with your bash environment variables.

Answer 2

a=5 is an argument to your script not an environment variable. to access the argument in the script use process.argv

https://nodejs.org/en/knowledge/command-line/how-to-parse-command-line-arguments/