How to use ansi-colors - 10 common examples

function checkProjectName(name, dependencies) {
  // Validate project name against NPM naming restriction
  // https://github.com/npm/cli/blob/latest/doc/files/package.json.md#name
  const validationResult = validateProjectName(name);
  if (!validationResult.validForNewPackages) {
    console.error(`Could not create a project called ${colors.red(`"${name}"`)} because of npm naming restrictions:`);
    printValidationResults(validationResult.errors);
    printValidationResults(validationResult.warnings);
    process.exit(1);
  }

  // Check if project name conflicts with existing NPM packages
  if (dependencies.indexOf(name) >= 0) {
    console.error(
      colors.red(`We cannot create a project called `) +
        colors.green(name) +
        colors.red(
          ` because a dependency with the same name exists.\n` +
            `Due to the way npm works, the following names are not allowed:\n\n`
        ) +
        colors.cyan(dependencies.map(depName => `  ${depName}`).join('\n')) +
        colors.red('\n\nPlease choose a different project name.')
    );
    process.exit(1);
  }
}

function renderChain(currentChain) {
    // If it's a lerna dependency, ignore it.
    if (currentChain.filter(item => lernaRegex.test(item)).length) {
        return;
    }

    //currentChain.reverse();
    console.log(currentChain.join(colors.bold(" ← "))); // →
}

try {
        // TODO: DRY with "up" command
        const knex = db.connect(db.thisUrl(name));
        const [batch, filenames] = await knex.migrate.latest();

        if (filenames.length > 0) {
          console.log(`Migration batch #${batch} applied!`);
          filenames.forEach(filename =>
            console.log(`↑ ${c.yellowBright(filename)}`));
          console.log();
        }
      } catch (err) {
        console.error(c.redBright('Knex migration failed:'), err);
        if (opts.switch) {
          console.log(
            `Switching back to ${c.yellowBright(current)}`
            + ' and dropping the new database...',
          );
          db.switchTo(current);
        }
        await knexFallback.raw(`drop database "${name}"`);
        console.log('Done.');
        throw new Error('Migration failed; database dropped.');
      }
      await printLatest();
    }

    return name;
  };
};

exports.handler = async (yargs) => {
  const db = require('../db')();
  const { verbose: explictlyVerbose } = yargs;
  const showMigrations = explictlyVerbose !== undefined ? explictlyVerbose : !!db.config.migrations;

  try {
    // TODO: refactor to use printLatestMigration (maybe that func can not print them?)
    const name = db.thisDb();
    let migration = [];
    if (showMigrations) {
      const knex = db.connectAsSuper(db.thisUrl(name));
      migration = await migrationOutput(knex, true);
    }

    console.log(`* ${c.yellowBright(name)} ${migration.join(' ')}`);
    process.exit(0);
  } catch (err) {
    const { message } = err;
    console.error(`postgres: ${c.redBright(message)}`);
    process.exit(1);
  }
};

const thisDbMigration = appliedMigrations.find(m => m.name === vcsMigrations[i].name);
    if (!thisDbMigration) {
      console.error(
        `Trying to cascade deletion but migration ${c.redBright(vcsMigrations[i].name)} `
          + 'could not be found in the database! Exiting.',
      );
      endProgram(1);
    }

    // execute the migration in our database and record it in the knex migrations table
    const { name, fullPath } = vcsMigrations[i];
    const { down: runDownMigration } = require(fullPath);
    try {
      await runDownMigration(knex, Promise);
      await deleteMigration(knex, thisDbMigration.id);
      console.log(`↓ ${c.redBright(name)}`);
    } catch (err) {
      console.error(`something went wrong running down from: ${fullPath}`);
      console.error(err);
    }
  }
  /* eslint-enable no-await-in-loop  */
  /* eslint-enable import/no-dynamic-require */

  // close our database connection
  await printLatest();
  return new Promise(resolve =>
    knex.destroy(() => {
      debug(`Down-migration to <${userInput}> finished!`);
      resolve();
    }));
};

requiredConfigUpdates.map( (requiredConfigField) => {
        // Error if config that must be set is still the default value.
        if ( nameFieldDefaults[requiredConfigField] === config.theme[requiredConfigField] ){
            log(colors.red(`${colors.bold('Error:')} the theme ${requiredConfigField} must be different than the default value ${nameFieldDefaults[requiredConfigField]}.`));
            process.exit(1);
        }

    });

function loadConfig() {
  log('Loading config file...');

  if (checkFileExists('config.yml')) {
    // config.yml exists, load it
    log(colors.bold(colors.cyan('config.yml')), 'exists, loading', colors.bold(colors.cyan('config.yml')));
    let ymlFile = fs.readFileSync('config.yml', 'utf8');
    return yaml.load(ymlFile);

  } else if(checkFileExists('config-default.yml')) {
    // config-default.yml exists, load it
    log(colors.bold(colors.cyan('config.yml')), 'does not exist, loading', colors.bold(colors.cyan('config-default.yml')));
    let ymlFile = fs.readFileSync('config-default.yml', 'utf8');
    return yaml.load(ymlFile);

  } else {
    // Exit if config.yml & config-default.yml do not exist
    log('Exiting process, no config file exists.');
    log('Error Code:', err.code);
    process.exit(1);
  }
}

minViewport = contextMinViewport
  if (argv.minviewport !== undefined) {
    minViewport = Math.max(contextMinViewport, argv.minviewport)
  }
  maxViewport = contextMaxViewport
  if (argv.maxviewport !== undefined) {
    maxViewport = Math.min(contextMaxViewport, argv.maxviewport)
  }

  if (argv.verbose) {
    console.log(
      color.green(
        `Viewports will be considered from ${color.white(
          minViewport + 'px',
        )} to ${color.white(maxViewport + 'px')}`,
      ),
    )
  }

  /* ======================================================================== */
  if (argv.verbose) {
    console.log(
      color.bgCyan.black(
        '\nStep 2: get variations of image width across viewport widths',
      ),
    )
  }

  const VIEWPORT = {
    width: minViewport,
    height: 2000,

export async function builder(version: string, config: BuildSchema): Promise {

    // log we are starting the shared build tasks
    log(`${colors.bgBlue(" ")} Beginning shared build tasks.`);

    try {

        // run global tasks
        await Promise.all(config.tasks.map(task => task(version, config)));

        log(`${colors.bgGreen(" ")} Finished shared build tasks.`);

    } catch (e) {

        log(`${colors.bgRed(" ")} ${colors.bold(colors.red(`Error in shared build tasks.`))}.`);
        log(`${colors.bgRed(" ")} ${colors.bold(colors.red("Error:"))} ${colors.bold(colors.white(typeof e === "string" ? e : JSON.stringify(e)))}`);
        throw e;
    }

    // run the per package tasks
    return config.packages.reduce((pipe: Promise, pkg) => {

        if (typeof pkg === "string") {
            pkg = { name: pkg };
        }

        // gate the package names so folks don't try and run code down the line
        if (!/^[\w-]+$/i.test(pkg.name)) {
            throw Error(`Bad package name "${pkg.name}".`);
        }

        const projectFolder = path.join(config.packageRoot, pkg.name);

// throw error to console
            log(colors.bold(colors.red(err.name + ': ' + err.message)));

            // throw notification
            notifier.notify({
                title: 'ROARRRRRRRRRR!',
                message: 'JavaScript gone wrong.',
                sound: 'Basso',
                contentImage: __dirname + '/../assets/trex.png'
            });
        })
        .pipe(source('script.js'))
        .pipe(buffer())
        .pipe(sourcemaps.init({loadMaps: true}))
        .pipe(process.env.APP_ENV === 'production' ? uglify() : through())
        .pipe(through((log(colors.white('JS files generated:')))))
        .pipe(size({title: 'Scripts:', showFiles: true}))
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest(config.scripts.destinationFolder))
        .pipe(browserSync.stream());
}