fxa/_scripts/check_node_version.js

const check = require("check-node-version");

check(
    { node: ">= 8", npm: ">= 6" },
    (error, results) => {
        if (error) {
            console.error(error);
            return;
        }

        if (results.isSatisfied) {
            console.log("Node and nvm version ok");
            return;
        }

        console.error("Some package version(s) failed!");

        for (const packageName of Object.keys(results.versions)) {
            if (!results.versions[packageName].isSatisfied) {
                if(packageName === 'npm')
                  console.error(`Npm version must be > 6 . Run the following command to upgrade npm "npm i -g npm@6"`);
                else if(packageName === 'node')
                  console.error(`Node version must be > 8`);
                  if(process.platform === 'darwin')
                    console.log("Use this if you do not rely on other node.js programs on your system: Find the latest Node 8 LTS .pkg download at nodejs.org/en/download/ and install it.")
                else
                  console.error(`Missing ${packageName}.`);

                process.exit(1);
            }
        }
    }
);