named parameter to npm run script

Question

I would like to pass a named parameter to an npm run script so I can do something like the following:

"scripts":{
    "say-hello":"echo $greeting && ls"
 }

 npm run hello --greeting=hello

I'd like it to then put 'hello' in place of the $greeting variable, echo the command and then do the ls (this is obviously just a simple example of a chained command)

Trippet

Answer 1

Just found out that this works:

"scripts":{
  "say-hello" : "echo $npm_config_greeting && ls"
}

Edit:

Any environment variables that start with npm_config_ will be interpreted as a configuration parameter. For example, putting npm_config_foo=bar in your environment will set the foo configuration parameter to bar.

npm docs

Stoneman

How did you get this to work? I'm trying and I can't figure it out. – Aboral

@Aboral here's a minimal package.json, call with npm run say-hello --greeting="hello world" ([email protected]) – Stoneman

That's what I did, and still I get $npm_config_greeting echoed. Problem was, that I tried it on Windows and despite running it in bash, echo still expected variable to be in form %npm_config_greeting%. I'll delete my answer, as it is wrong. – Aboral

@Aboral oh right, Windows works differently when it comes to environment variables (which these are). Good point. – Stoneman

@Stoneman do you know if there's any work around or options for windows? – Trippet

@Trippet sorry, no, I don't have Windows myself so can't check for an alternative. – Stoneman

In case anybody else is stuck with this - the only way I could get it to work with powershell (pwsh specifically) is to use $env:variable where variable is npm_config_{name of variable passed to script as argument} . Strangely obtuse. – Aerolite

Answer 2

Another way is to simply add the following '--' followed by your desired param(s). This would be for named parameters that '=' a value. Please note the underlying process in this example, a protractor call, expects a Url arg.

npm run e2e -- --Url="https://yoururlhere.com"

Evertor