ft/aurelia_project/tasks/lint-js.js

import gulp from 'gulp';
import project from '../aurelia.json';
import eslint from 'gulp-eslint';
import {CLIOptions} from 'aurelia-cli';

// linting configuration in is .eslintrc.json file in project root folder

function lintJsSrc() {
  if (CLIOptions.hasFlag('watch')) {
    return gulp.src(project.jsLinter.source)
      .pipe(eslint())
      .pipe(eslint.format());
  }
  return gulp.src(project.jsLinter.source)
    .pipe(eslint())
    .pipe(eslint.format())
    .pipe(eslint.failAfterError());
}

// linting tests is les strict - console.log and
function lintJsTests() {
  if (CLIOptions.hasFlag('watch')) {
    return gulp.src(project.jsLinter.testSource)
      .pipe(eslint({
        'rules': {
          'no-console': ['warn'],
          'no-unused-vars': ['warn'],
          'quotes': ['off', 'single']
        }
      }))
      .pipe(eslint.format());
  }
  return gulp.src(project.jsLinter.testSource)
    .pipe(eslint({
      'rules': {
        'no-console': ['warn'],
        'no-unused-vars': ['warn'],
        'quotes': ['off', 'single']
      }
    }))
    .pipe(eslint.format())
    .pipe(eslint.failAfterError());
}

export default gulp.parallel(lintJsSrc, lintJsTests);