Gulp 4 watch() TypeError: expected a string

Question

I have encountered a problem while starting gulp. The info I got is from https://coder-coder.com/gulp-4-walk-through/ and https://www.youtube.com/watch?v=-lG0kDeuSJk.

my gulpfile.js

// Initialize modules
const { src, dest, watch, series, parallel } = require('gulp');
const autoprefixer = require('autoprefixer');
const cssnano = require('cssnano');
const concat = require('gulp-concat');
const postcss = require('gulp-postcss');
const replace = require('gulp-replace');
const sass = require('gulp-sass');
const sourcemaps = require('gulp-sourcemaps');
const terser = require('gulp-terser');

// File path variables
const files = {
  scssPath: './assets/styles/sass/**/*.scss',
  jsPath: './assets/js/**/*.js'
}

// Sass taks
function scssTask(){
 return src(files.scssPath)
   .pipe(sourcemaps.init())
   .pipe(sass())
   .pipe(postcss([ autoprefixer(), cssnano() ]))
   .pipe(sourcemaps.write('.'))
   .pipe(dest('dist'));
}

 // JS taks
 function jsTask(){
   return src(files.jsPath)
       .pipe(concat('main.js'))
       .pipe(terser())
       .pipe(dest('dist'));
 }

 // Cachebusting taks
 const cbString = new Date().getTime();
 function cacheBustTask(){
   return src(['index.html'])
       .pipe(replace(/cb=\d+/g, 'cb=' + cbString))
       .pipe(dest('.'));
 }     

 // Watch taks
 function watchTask(){
   watch([files.scssPath, files.jsFiles],
     series(
       parallel(scssTask, jsTask),
       cacheBustTask
     )
   );
 }
 // Default task
 exports.default = series(
   parallel(scssTask, jsTask),
   cacheBustTask,
   watchTask
 );

when I start command gulp in the folder i get an error saying:

[09:53:25] 'watchTask' errored after 1.81 ms

[09:53:25] TypeError: expected a string

at module.exports (D:\Web-Development\Startup\practise\sassStructure-Copy\node_modules\is-negated-glob\index.js:5:11)

at sortGlobs (D:\Web-Development\Startup\practise\sassStructure-Copy\node_modules\glob-watcher\index.js:66:18)

at Array.forEach (<anonymous>)

at watch (D:\Web-Development\Startup\practise\sassStructure-Copy\node_modules\glob-watcher\index.js:63:18)

at Gulp.watch (D:\Web-Development\Startup\practise\sassStructure-Copy\node_modules\gulp\index.js:48:10)

at watchTask (D:\Web-Development\Startup\practise\sassStructure-Copy\gulpfile.js:46:3)

at bound (domain.js:420:14)

at runBound (domain.js:433:12)

at asyncRunner (D:\Web-Development\Startup\practise\sassStructure-Copy\node_modules\async-done\index.js:55:18)

at processTicksAndRejections (internal/process/task_queues.js:75:11)

[09:53:25] 'default' errored after 721 ms

How can I resolve this? It expects string and i give it a string jet it doesn't work. I have put

   function watchTask(){
      watch([files.scssPath, files.jsFiles],
        series(
          parallel(scssTask, jsTask),
          cacheBustTask
        )
      );
    }

Then I get no errors, watchTask starts but no files get updated, just silence haha

Here is folder structure: [a link]https://i.ibb.co/LPYsxWG/brisi.png

Could someone explain me why it doesn't know it's string like on everyone's project and i must convert it to string with toString() and why the watch function watchTask doesn't recognize any updates? Thank's in advance.

Answer 1

It seems you are using the wrong variable name. jsPath should be used. Either way, try to make it more readable... for example you can use:

const watch = function() {
    gulp.watch("./assets/styles/sass/**/*.scss", {usePolling : true}, gulp.series(css));
    gulp.watch("./assets/js/**/*.js", {usePolling : true}, gulp.series(js));
};

If you use this code it's not necessary for watch to require gulp in the first line of your code.

In the end make the block like this:

 // Default task
 exports.default = series(
   parallel(scssTask, jsTask),
   cacheBustTask,
   watch
 );

exports.watch = watch;