Let's say you would like to extract multiple values from your package.json
file into an ES6 module that you can easily import. You might want access to
the version, the package name, the homepage URL, etc.
You could use import.meta.url
to find the file, read it, JSON parse it, and
extract the needed bits. Now you'd like to use your code from the web, and
all of that falls apart. Not only do you have to bundle the whole
package.json
file, exposing information that you might not want to make
available to web users, but you also have to figure out how to get the
readFile bits to do the right thing.
Instead, use package-extract.
npm install -D package-extract
npx package-extract -o lib/package.js name version homepage
Note that you can extract fields that have structure, like scripts
.
It is most convenient to run this script when you run npm version
. To do
so, add this to your package.json:
{
"scripts": {
"version": "package-extract && git add package.js"
}
}
import {homepage, name, version} from './package.js';
// Generated by package-extract v0.0.0
// Do not modify by hand.
export const name = 'package-extract';
export const version = '0.0.0';
export const homepage = 'https://github.com/hildjj/package-extract';
Usage: package-extract [options] [fields...]
Arguments:
fields fields to extract from package file (default:
["version"])
Options:
-d, --double use double quotes
-i, --indent <number> number of spaces to indent. -1 for tab. 0 for no
newlines. (default: 2)
-o, --output <filename> name of output file, relative to package.json. Use
"-" for stdout. (default: "package.js")
-p, --package package file to extract from, found from cwd,
searching up
-s, --semi add semicolons to the end of each variable
--startDir <dir> start looking from this directory, toward the root
(default: process.cwd())
-t, --trailing Add trailing commas
-V, --version output the version number
-h, --help display help for command
import {packageExtract} from 'package-extract';
// All options are optional, have the same defaults as the CLI.
await packageExtract({
double: false,
indent: 2,
output: 'package.js',
package: 'package.json',
semi: false,
startDir: process.cwd(),
trailing: false,
}, ['version', 'name']);
Why not use?
- genversion: Doesn't extract fields other than version.
- package-json-versionify: Doesn't extract fields other than version, only works in a browserify setup. Doesn't support ES6.
- browserify-versionify: Doesn't extract fields other than version, only works in a browserify setup.