Gulpfile.js

var gulp = require('gulp');
var eslint = require('gulp-eslint');
var rename = require('gulp-rename');
var uglify = require('gulp-uglify');

gulp.task('lint', () => {
    // 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(['jquery.time-to.js'])
        // 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('build', () => {
    return gulp.src('jquery.time-to.js')
        .pipe(uglify({
            preserveComments: 'license'
        }))
        .pipe(rename({
            suffix: '.min'
        }))
        .pipe(gulp.dest('.'))
});

gulp.task('default', ['lint', 'build']);