if_satisfy_node_version.js

var child_process = require('child_process');
var packageJson = require('./package.json');

var requiredNodeVersion = packageJson.required_node_version;
var requiredNpmVersion = packageJson.required_npm_version;

var colors = {
  green: "\x1b[32m",
  red: "\x1b[31m",
}

console.log('Checking if node version satisfies required version' + ' (' + requiredNodeVersion + ')');

var currentNodeVersion = process.version;

if (currentNodeVersion.substr(1, requiredNodeVersion.length) < requiredNodeVersion) {
  console.error(colors.red, '\n   ERROR: Installed Node version does not satisfy project\'s requred Node Version (' + currentNodeVersion + ' < v' + requiredNodeVersion + ') \n' );

  process.exit(1);
} else {
  console.log(colors.green, '\u2713 Node Version checked')
}

child_process.exec('npm --version', function(error, currentNpmVersion, stderr) {
  currentNpmVersion = currentNpmVersion.replace('\n', '');

  if (currentNpmVersion.substr(0, requiredNpmVersion.length) < requiredNpmVersion) {
    console.error(colors.red, '\n   ERROR: Installed NPM version does not satisfy project\'s requred NPM Version (' + currentNpmVersion + ' < v' + requiredNpmVersion + ') \n' );

    process.exit(1);
  } else {
    console.log(colors.green, '\u2713 NPM Version checked')
  }

})