How to compile and bundle react 16.9 using gulp 4.0.1? - gulp-4

Question

I have an existing project, I used React 16.9. Now, I want to implement Gulp 4.0.1 to build it in the server. I am running in windows 10.
In my components, I am using import form
I tried using this gulpfile.js, its very simple.
var gulp = require('gulp'),
browserify = require('browserify'),
source = require('vinyl-source-stream'),
buffer = require('vinyl-buffer');
var BUILD_DIR = 'buildtest/';
function compile() {
var bundler = browserify('src/index.js');
return bundler
.transform('babelify', { presets: ['es2015', 'react'] })
.bundle()
.pipe(source('index.js'))
.pipe(buffer())
.pipe(gulp.dest(BUILD_DIR));
}
gulp.task('build:js', function() {
return compile();
})
gulp.task('build', ['build:js'])
Now by running the gulp command it gives me this error:
λ gulp
assert.js:350
throw err;
^
AssertionError [ERR_ASSERTION]: Task function must be specified
at Gulp.set [as _setTask] (D:\myprojectfolderpath\node_modules\undertaker\lib\set-task.js:10:3)
at Gulp.task (D:\myprojectfolderpath\node_modules\undertaker\lib\task.js:13:8)
at Object.<anonymous> (D:\myprojectfolderpath\gulpfile.js:84:6)
at Module._compile (internal/modules/cjs/loader.js:701:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
at Module.load (internal/modules/cjs/loader.js:600:32)
at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
at Function.Module._load (internal/modules/cjs/loader.js:531:3)
at Module.require (internal/modules/cjs/loader.js:637:17)
at require (internal/modules/cjs/helpers.js:22:18)

Answer 1

According to the gulp's task Documentation gulp.task([taskName], taskFunction) second argument the 'taskFunction' needs to use either a gulp.series() or gulp.parallel.
Before 4.0 it was possible to define the task as you did, but this changed in 4.0.
Changing your gulp.task('build', ['build:js']) into gulp.task('build', gulp.series('build:js')) should fix the issue.