gulpfile.js

var gulp = require('gulp');
var eslint = require('gulp-eslint');
var gulpIf = require('gulp-if');

var fix = false;

function isFixed(file) {
  // Has ESLint fixed the file contents?
  return file.eslint != null && file.eslint.fixed;
}

gulp.task('eslint:src', function() {
  return gulp.src([
      'src/**',
    ])
    // eslint() attaches the lint output to the eslint property
    // of the file object so it can be used by other modules.
    .pipe(eslint({
      fix: fix,
    }))
    // eslint.format() outputs the lint results to the console.
    // Alternatively use eslint.formatEach() (see Docs).
    .pipe(eslint.format())
    // To have the process exit with an error code (1) on
    // lint error, return the stream and pipe to failAfterError last.
    .pipe(eslint.failAfterError())
    .pipe(gulpIf(isFixed, gulp.dest('src')));
});

gulp.task('eslint:docs', function() {
  return gulp.src([
      'docs/src/**/*.{js,jsx}',
    ])
    .pipe(eslint({
      fix: fix,
    }))
    .pipe(eslint.format())
    .pipe(eslint.failAfterError())
    .pipe(gulpIf(isFixed, gulp.dest('docs/src')));
});

gulp.task('eslint:test', function() {
  return gulp.src([
      'test/**/*.{js,jsx}',
    ])
    .pipe(eslint({
      fix: fix,
    }))
    .pipe(eslint.format())
    .pipe(eslint.failAfterError())
    .pipe(gulpIf(isFixed, gulp.dest('test')));
});