gulpfile.js

const gulp = require('gulp');
const fs = require('fs');
const del = require('del');
const $ = require('gulp-load-plugins')();

// Utility to ignore unnecessary files
// when generating the glob patterns array for gulp.src()
function addDefSrcIgnore (srcArr) {
  return srcArr.concat([
    '!node_modules{,/**}',
    '!private{,/**}',
    '!dist{,/**}',
    '!.git{,/**}',
    '!**/.DS_Store'
  ]);
}

// JavaScript and JSON linter
gulp.task('lint', function () {
  return gulp.src(addDefSrcIgnore(['**/*.js', '*.json']), {dot: true})
    .pipe($.eslint({dotfiles: true}))
    .pipe($.eslint.format())
    .pipe($.eslint.failAfterError());
});

// Remove solutions from exercises
gulp.task('remove-solutions', ['lint'], function () {
  del.sync('dist');
  return gulp.src(addDefSrcIgnore(['**']), {dot: true})
    .pipe($.replace(/^\s*(\/\/|<!--|\/\*)\s*REMOVE-START[\s\S]*?REMOVE-END\s*(\*\/|-->)?\s*$/gm, ''))
    .pipe(gulp.dest('dist'));
});

// Prepare for distribution to students
gulp.task('dist', ['remove-solutions'], function () {

  function removeMaster (str) {
    var strArr = str.split('-');
    strArr[strArr.length - 1] === 'master' && strArr.pop();
    return strArr.join('-');
  }

  const npmConfig = require('./package.json');
  npmConfig.name = removeMaster(npmConfig.name);
  npmConfig.repository.url = removeMaster(npmConfig.repository.url);
  npmConfig.scripts['precommit'] = 'gulp lint';
  fs.writeFileSync('dist/package.json', JSON.stringify(npmConfig, null, 2));

  const esLintConfig = require('./.eslintrc.json');
  esLintConfig.rules['no-undef'] = 'off';
  esLintConfig.rules['no-unused-vars'] = 'off';
  fs.writeFileSync('dist/.eslintrc.json', JSON.stringify(esLintConfig, null, 2));

});