Can I chain npm configuration entries? - node.js

Question

Use of the npm config section is simple, and cool, but I've run into one restriction with it: a config entry does not get expanded, so one cannot chain them, nor even access non-config values s.a. package version within the config.
Sample:
{
"name": "myproj",
"version": "0.1.2",
"//": "Here, '$npm_package_version' is not expanded",
"config": {
"target": "dist/myproj-$npm_package_version.js"
},
"scripts": {
"echo": "echo $npm_package_config_target",
}
}
This gives:
dist/myproj-$npm_package_version.js
instead of:
dist/myproj-0.1.2.js
Is there anything I can do about it? Chaining values like this is a useful feature - I'm surprised nom doesn't do it. Is there a reason not to?
References:
Node.js: How to setup different variables for prod and staging
How to use npm as a build tool

Answer 1

There's a few of ways this could be handled.
The simplest way is probably just to eval the string
{
"name": "myproj",
"version": "0.1.2",
"config": {
"target": "dist/myproj-$npm_package_version.js"
},
"scripts": {
"echo": "eval echo $npm_package_config_target"
}
}
If you're not comfortable with eval then you could either manually concat the string within the script:
{
"name": "myproj",
"version": "0.1.2",
"config": {
"target_prefix": "dist/myproj-",
"target_suffix": ".js"
},
"scripts": {
"echo": "echo $npm_package_config_target_prefix$npm_package_version$npm_package_config_target_suffix",
}
}
Or you could do away with using npms config and write a quick script instead, which can be composed with others:
{
"name": "myproj",
"version": "0.1.2",
"scripts": {
"config:target": "echo dist/myproj-$npm_package_version.js",
"echo": "echo $(npm run config:target)"
}
}