npm-package-env

conveniently get npm_package_ variables using property accessors

installation

npm i npm-package-env -S

overview

this package provides easy access to package.json variables (or per-package config settings) via property accessors - both .dot and [bracket] notation are supported.

examples

all examples assume my-npm-script.js is run via npm run, i.e. the package.json has something like this:

"scripts": {
    "start": "my-npm-script"
}

getting a string

my-npm-script.js

const npmEnv = require('npm-package-env')._in('config');
npmEnv['dev-server'].port._as('string'); // -> '7777'

package.json

"config": {
    "dev-server": {
        "port": 7777
    }
}

getting an array

my-npm-script.js

const npmEnv = require('npm-package-env');
npmEnv.keywords._as('array'); // -> ['foo', 'bar', 'wat']
npmEnv.keywords._as('array')[1]; // -> 'bar'

package.json

"keywords": [
    "foo", "bar", "wat"
]

getting an object by keys

my-npm-script.js

const npmEnv = require('npm-package-env');
npmEnv.dependencies._as('object', ['auto-exports']); // -> {'auto-exports': '14.1.3'}

package.json

"dependencies": {
    "auto-exports": "14.1.3",
    "npm-package-env": "^2.0.21"
}

API

.<property> / [<'property-name'>] (property accessors)

used to walk deeper into the package.json object tree. equivalent to stating the full variable path in process.env.npm_package_<var_path>.

Returns: {I} a self reference (chainable).

_as(type, [...indices])

converts the current variable value to the specified type and returns it.

type {String} the result type, one of: 'string', 'array' or 'object'.
indices {*} (optional) when passing 'object' as the type, this is a whitelist of property keys that will be included in the result object.

Returns: {String|Array|Object} the current variable value as the specified type, or undefined if no such variable was found.

_in([...prefixes])

initializes a new instance in the specified location, starting from npm_package_. for example, to start every next property access from npm_package_config_server_auth:

let authConfig = npmEnv._in('config', 'server', 'auth');
authConfig.user._as('string');
authConfig.policies._as('array');

prefixes {*} (optional) a list of prefix segments to bind to the new instance.

Returns: {I} a new instance, bound to the passed prefix.