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Why is merge-stream requiring async completion signal?

I'm in the process of migrating from gulp#3.9.1 to gulp#4.0.2 and upgrading my gulp dependencies in the process. I have the following task in my gulpfile, where you can assume directories is just an array of directories I want to perform this operation on:
var gulp = require('gulp');
var ngAnnotate = require('gulp-ng-annotate'); //annotates dependencies in Angular components
var rev = require('gulp-rev'); //appends a hash to the end of file names to eliminate stale cached files
var revReplace = require('gulp-rev-replace');
var uglify = require('gulp-uglify'); // minimizes javascript files
var compressCss = require('gulp-minify-css');
var useref = require('gulp-useref'); // replaces style and script blocks in HTML files
var filter = require('gulp-filter');
var merge = require('merge-stream');
var sourcemaps = require('gulp-sourcemaps');
function minify() {
var tasks = directories.map(function (directory) {
var cssFilter = filter("**/all.min.css", {restore:true});
var jsAppFilter = filter("**/app.min.js", {restore:true});
var jsFilter = filter("**/*.js", {restore:true});
return gulp.src(dstBasePath + directory + "index.html", {allowEmpty: true})
.pipe(useref())
.pipe(cssFilter)
.pipe(compressCss({keepSpecialComments:false}))
.pipe(rev())
.pipe(cssFilter.restore)
.pipe(jsAppFilter)
.pipe(sourcemaps.init())
.pipe(ngAnnotate({add:true, single_quotes:true}))
.pipe(jsAppFilter.restore)
.pipe(jsFilter)
.pipe(uglify())
.pipe(rev())
.pipe(jsFilter.restore)
.pipe(revReplace())
.pipe(sourcemaps.write('.')) // sourcemaps need to be written to same folder for Datadog upload to work
.pipe(gulp.dest(dstBasePath + directory))
});
return merge(tasks);
}
Why would this result in the error "Did you forget to signal async completion?" from Gulp when running the task? Note that I'm using Gulp 4. I've tried passing a callback done to this task, and adding .addListener('end', done) to the final pipe, but this causes my merged stream to end prematurely (presumably when the first one ends). So perhaps one of these plugins is not signaling when it's completed, but how would you even get this to work otherwise? Thanks for any insight you can provide.

return merge(folders.map(function (folder) { // this has worked for me in the past
as has this form without merge
gulp.task('init', function (done) {
var zips = getZips(zipsPath);
var tasks = zips.map(function (zip) {
return gulp.src(zipsPath + "/" + zip)
.pipe(unzip({ keepEmpty: true }))
.pipe(gulp.dest(path.join("src", path.basename(zip, ".zip"))))
.on('end', function() { // this bit is necessary
done();
});
});
return tasks;
});

Gulp 4 requires that you signal async completion. There's some good information about it in this answer to a similar question:
Gulp error: The following tasks did not complete: Did you forget to signal async completion?
I had a similar case where I was returning a merged set of tasks, and I was able to resolve the error by making the function async and awaiting the merge. My case looked something like this:
gulp.task("build", async function () {
...
return await merge(tasks);
});
so I think you should be able to do something like
async function minify(){
...
return await merge(tasks);
}

Gulp 4 watch doesn't detect changes

Is it possible with gulp v.4.0.0 to watch for files outside of the folder where gulpfile.js is located?
In older gulp it was possible to set file path to ../../someFile.css and watch for its changes, but in v4 it doesn't detect changes for the same path.
// snip....
let rootFolder = '..\..\root\';
// Watch function
let watchThis = (filePath, gulpTasks) => {
gulp.watch(filePath, gulp.series(gulpTasks))
.on('change', function(path) {
console.log(`${chalk.blue('Changed')}: ${chalk.yellow(path)}`);
})
.on('unlink', function(path) {
console.log(`${chalk.red('Deleted')}: ${chalk.yellow(path)}`);
});
}
// Watch task configuration
let watchFiles = () => {
watchThis([`${rootFolder}/style1.scss`, `${rootFolder}/style2.scss`], 'scss')
watchThis('./js/main.js', 'js')
}
// Final watch task
gulp.task('watch', gulp.series(
'development',
gulp.parallel(
watchFiles,
'startLiveServers'
)
));
// ...snip
Changes to files ['../../style1.scss', '../../style2.scss'] will not be detected, but they will be for './js/main.js'. Am I missing something?

Problem with new Gulp 4 watch task is in paths. Unlike watch task from Gulp 3, new version is unforgiving and requires correct path structure with correct paths separators.
So instead of using paths that may result in ..\\..\\root\\/style1.scss, we must convert paths to proper structure like ../../root/style1.scss.
This simple function helps and the rest is handled by gulp and nodejs
let fixPath = (oldPath) => {
const pathString = oldPath;
const fix = /\\{1,}|\/{1,}/;
return pathString.replace(new RegExp(fix, 'gm'), '/').replace(new RegExp(fix, 'gm'), '/')
}

Set a different destination folder structure than the source folder

I'm running a gulp task to minify and move JS files.
var js_modules = 'application/modules/**/assets/js/*.js';
var js_dist_modules = 'assets/js/modules/';
gulp.task('dev_scripts', function() {
return gulp.src(js_modules)
.pipe(plumber())
.pipe(uglify())
.pipe(gulp.dest(js_dist_modules));
});
With this task the output is:
Source:
application/modules/users/assets/js/users.js
application/modules/menu/assets/js/menu.js
Destination:
assets/js/modules/users/assets/js/users.js
assets/js/modules/menu/assets/js/menu.js
And I want the destinations to be:
assets/js/modules/users/users.js
assets/js/modules/menu/menu.js
How do I achiev that?

I used gulp-rename:
var rename = require('gulp-rename');
var js_modules = 'application/modules/**/assets/js/*.js';
var js_dist_modules = 'assets/js/modules/';
gulp.task('dev_scripts', function() {
return gulp.src(js_modules)
.pipe(plumber())
.pipe(uglify())
.pipe(rename(function(file) {
file.dirname = js_dist_modules + file.basename;
}))
.pipe(gulp.dest(.));
});

Using gulp-flatten it appears something like this may work (untested):
var flatten= require('gulp-flatten);
var js_modules = 'application/modules/**/assets/js/*.js';
var js_dist_modules = 'assets/js/modules/';
gulp.task('dev_scripts', function() {
return gulp.src(js_modules)
.pipe(plumber())
.pipe(uglify())
.pipe(flatten({ subPath: [2, 1] } ))
.pipe(gulp.dest(js_dist_modules));
});
You could play with the subPath numbers to get the third (2) or whichever subDirectory you want.
This answer is more general than the previous using rename in case your desired directories - in your case the glob ** - are not the same as files' basenames.

Get Gulp watch to perform function only on changed file

I am new to Gulp and have the following Gulpfile
var gulp = require('gulp');
var jshint = require('gulp-jshint');
var concat = require('gulp-concat');
var rename = require('gulp-rename');
var uglify = require('gulp-uglify');
gulp.task('compress', function () {
return gulp.src('js/*.js') // read all of the files that are in js with a .js extension
.pipe(uglify()) // run uglify (for minification)
.pipe(gulp.dest('dist/js')); // write to the dist/js file
});
// default gulp task
gulp.task('default', function () {
// watch for JS changes
gulp.watch('js/*.js', function () {
gulp.run('compress');
});
});
I would like to configure this to rename, minify and save only my changed file to the dist folder. What is the best way to do this?

This is how:
// Watch for file updates
gulp.task('watch', function () {
livereload.listen();
// Javascript change + prints log in console
gulp.watch('js/*.js').on('change', function(file) {
livereload.changed(file.path);
gutil.log(gutil.colors.yellow('JS changed' + ' (' + file.path + ')'));
});
// SASS/CSS change + prints log in console
// On SASS change, call and run task 'sass'
gulp.watch('sass/*.scss', ['sass']).on('change', function(file) {
livereload.changed(file.path);
gutil.log(gutil.colors.yellow('CSS changed' + ' (' + file.path + ')'));
});
});
Also great to use gulp-livereload with it, you need to install the Chrome plugin for it to work btw.

See incremental builds on the Gulp docs.
You can filter out unchanged files between runs of a task using the gulp.src function's since option and gulp.lastRun

hbsfy outputs hbsfy code on compile - using Gulp + Browserify

I am trying to get any variation of hbsfy or browserify-handlebars to compile correctly using browserify. Compiling results in the handlebars.js(hbsfy) code outputting to my browser. I've tried just using the browserify command browserify -t hbsfy app.js > bundle.js but it doesn't change anything
I haven't the reputation to post images but basically this is the output:
var templater = require("handlebars/runtime").default.template;module.exports = templater(function (Handlebars,depth0,helpers,partials,data) { this.compilerInfo = [4,'>= 1.0.0']; helpers = this.merge(helpers, Handlebars.helpers); data = data || {}; var buffer = "", stack1, helper, functionType="function", escapeExpression=this.escapeExpression; buffer += "
Hello "; if (helper = helpers.name) { stack1 = helper.call(depth0, {hash:{},data:data}); } else { helper = (depth0 && depth0.name); stack1 = typeof helper === functionType ? helper.call(depth0, {hash:{},data:data}) : helper; } buffer += escapeExpression(stack1) + "
"; return buffer; });
My template (template.hbs) is simply <h1>Hello {{name}}</h1>
My gulpfile setup:
var gulp = require('gulp');
var livereload = require('gulp-livereload');
var browserify = require('gulp-browserify');
var hbsfy = require('browserify-handlebars');
//var hbsfy = require('hbsfy'); //this one shows up the same way
gulp.task('scripts', function() {
return gulp.src('./app/app.js')
.pipe(browserify({
transform: [hbsfy]
}))
.pipe(rename('bundle.js'))
.pipe(gulp.dest('./build/js'))
.pipe(connect.reload());
});
and my js file:
var Handlebars = require('hbsfy/runtime');
var $ = require('jquery'),
router = require('./router/routerDefault'),
template = require('./template.hbs');
$(document).ready(function(){
document.body.innerHTML = template({name: 'browserify'});
})
Does anyone have any experience on how to handle this? Any suggestions would be heplful!

The cause of this issue is redundant compiling. Listing a transform in both the packages.json and the gulpfile.js will perform it twice, I believe. In my packages.json, I now just use this 'node':
"browserify": {
"transform": [
"hbsfy"
]
},
This will compile your templates for you. Your gulpfile.js DOES NOT require this section:
.pipe(browserify({
transform: [hbsfy]
}))
You can use either one. My scripts gulp task now looks like this:
gulp.task('scripts', function() {
return browserify('./app/app.js')
.bundle()
.pipe(source('bundle.js'))
.pipe(gulp.dest('./build/js'))
.pipe(connect.reload());
});

I am experiencing something similar.
Just curious, what OS are you using? Seems to affect Mac but Windows seems OK.
I'm not entirely sure what's causing this but I stopped using gulp-browserify as it is now blacklisted.
I followed the suggestions from this blog post and it seems to solve the issue: http://viget.com/extend/gulp-browserify-starter-faq
The last bit is most relevant.
EDIT:
While using gulp-browserify, I would also check if you've listed your transforms in package.json. I think you may only need to specify transforms in one place (either in gulpfile as you have now or in package.json).