@mlaursen/release-script/dist/getPackageManager.js

The release script I normally use for packages I publish to npm

import { readFile } from "node:fs/promises";
import { resolve } from "node:path";
export async function getPackageManager() {
    const rawPackageJson = await readFile(resolve(process.cwd(), "package.json"), "utf8");
    const packageJson = JSON.parse(rawPackageJson);
    if (typeof packageJson.volta === "object" && packageJson.volta) {
        const { volta } = packageJson;
        if ("pnpm" in volta) {
            return "pnpm";
        }
        if ("yarn" in volta) {
            return "yarn";
        }
        return "npm";
    }
    if (typeof packageJson.packageManager === "string") {
        const mgr = packageJson.packageManagerreplace(/@.+/, "");
        if (mgr === "pnpm" || mgr === "yarn" || mgr === "npm") {
            return mgr;
        }
        throw new Error(`Unsupported package mananger "${mgr}" in package.json`);
    }
    throw new Error("Unable to find a package manager");
}