gulpfile.js

var gulp = require('gulp');
var gutil = require('gulp-util');
var uglify = require('gulp-uglify');
var watch = require('gulp-watch');
var eslint = require('gulp-eslint');

gulp.task('scripts', function() {
    // corpo da tarefa 
    return gulp
            .src(['js/**/*.js'])
            .pipe(uglify())
            .pipe(gulp.dest('build/js'));      
});

gulp.task('watch', function() {
    // corpo da tarefa 
    gulp.watch('js/**/*.js', function(event) {
        gutil.log('File '+event.path+' was '+event.type+', running tasks...');
        gulp.run('scripts');
    });
});


var gulp = require('gulp'),
    eslint = require('gulp-eslint');
 
gulp.task('lint', function () {
    // ESLint ignores files with "node_modules" paths. 
    // So, it's best to have gulp ignore the directory as well. 
    // Also, Be sure to return the stream from the task; 
    // Otherwise, the task may end before the stream has finished. 
    return gulp.src(['**/*.js','!node_modules/**'])
        // eslint() attaches the lint output to the "eslint" property 
        // of the file object so it can be used by other modules. 
        .pipe(eslint())
        // 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());
});
 
gulp.task('default', ['lint'], function () {
    // This will only run if the lint task is successful... 
});