Running tasks in series, i.e. Task Dependency

gulp-run-tasks-in-series.js

// ref: https://github.com/gulpjs/gulp/blob/master/docs/recipes/running-tasks-in-series.md

// ----------- method 1 ----------- //

gulp.task('2', ['1'], function() {
    var stream = gulp.src()
        // do some concatenation, minification, etc.
        .pipe(gulp.dest());
    return stream; // return the stream as the completion hint

});

gulp.task('3', ['1'], function() {
    var stream = gulp.src()
        // do some concatenation, minification, etc.
        .pipe(gulp.dest());
    return stream;
});
gulp.task('3', ['1', '2']);
gulp.task('4', ['3']);

// ----------- method 2 ----------- //

gulp.task('2', ['1'], function() {
    // task '1' is done now
});
gulp.task('3', ['1', '2']);      // 1, 2 is syntax sugar, since only 2 is necessary
gulp.task('4', ['1', '2', '3']); // 1, 2, 3 is syntax sugar, since only 3 is necessary

// -------------------------------- //