How to read an external file list with grunt

Question

I'm trying to concatenate and then babelify and uglify files with Grunt.

I'd like to read an external file list, from a file where the files are written one for each line, newline separated.

I'm trying to use the following GruntFile.js, but Grunt says (after I added the src=['<%= jsFiles.toString().split("\n") %>'] line):

Running "browserify:dist1" (browserify) task
Warning: An error occurred while processing a template (Invalid or unexpected token). Use --force to continue.

Where is the error?

This is the GruntFile.js

module.exports = function(grunt) {
  grunt.initConfig({
    jsFiles: grunt.file.read('scripts/s.list'),
    env: {
        prod: {
            NODE_ENV: 'production'
        }
    },
    browserify: {
      dist1: {
        options: {
           transform: [
             ['babelify', {presets: ['es2015']}]
           ]
        },
        src: ['<%= jsFiles.toString().split("\n") %>'],
        dest: '/WebContent/js/libs/s.bundle.js'
      },
    },
    uglify: {
        my_target1: {
          files: {
            '/WebContent/js/libs/s.bundleuglified.js': ['/WebContent/js/libs/s.bundle.js']
          }
        },
      }    
  });

  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-browserify');
  grunt.loadNpmTasks('grunt-env');
  grunt.registerTask('default', ['release']);
  grunt.registerTask('release', ['env', 'browserify', 'uglify']);
};

Edit: I added a backslash to \n and the error has gone, but the babelify task gives me an empty file...

Edit2: I was able to read the file list using the following two lines at the beginning of the GruntFile.js

  const jsFiles = grunt.file.read('scripts/s.list');
  const jsFilesArray = jsFiles.toString().split("\n");

and then

src: jsFilesArray.slice(0, jsFilesArray.length-1),

because the last element was '' and it gave the error Warning: must provide pattern” as Beniamin H suggested.

Edit3: I found that the babelify task was reading the files in alphabetical order, so I had to first concat them, as explained here, and then babelify and uglify

score 1 · Accepted Answer · answered Jan 12 '19 at 19:09

1

You don't need to use any '<%= %>'. The file is read synchronously into jsFiles property and it can be used immediately. You may want to specify encoding for grunt.file.read to get a string: https://gruntjs.com/api/grunt.file#grunt.file.read

answered Jan 12 '19 at 19:09

Beniamin H

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So, what should I write for src in your opinion? Only src = 'jsFiles.toString().split("\n")' ? – cdarwin Jan 12 '19 at 19:20
I cannot check it now but something like this should work: `src: this.jsFiles.toString().split("\n"),` – Beniamin H Jan 12 '19 at 19:24
this gives `>> TypeError: Cannot read property 'toString' of undefined ` – cdarwin Jan 12 '19 at 19:26
Ahh - yes, you may read a file to a variable, not into config object. `const jsFiles = grunt.file.read('scripts/s.list');` and then: `src: jsFiles.toString().split("\n")` – Beniamin H Jan 12 '19 at 19:30
You can do it the first line of the function. – Beniamin H Jan 12 '19 at 19:31
This way it works if I put two backslashes before n, but unfortunately I get an empty bundle - with a single backslash I get this error : `Warning: must provide pattern` – cdarwin Jan 12 '19 at 19:38
Probably you need to specify `dist1` for your browserify task: `grunt.registerTask('release', ['env', 'browserify:dist1', 'uglify']);` – Beniamin H Jan 12 '19 at 19:47
Or omit wrapping browserify options into `dist1`: ```browserify: { options: {...}, src: ... },``` – Beniamin H Jan 12 '19 at 19:48
About _"Warning: must provide pattern"_: https://stackoverflow.com/questions/26233743/grunt-watch-repeatedly-showing-warning-must-provide-pattern – Beniamin H Jan 12 '19 at 19:51
The file was ok, I was able to read the file list as I explain in Edit2. Thank you for the link to the must provide pattern error. Unfortunately it seems the file list is being read in a different order that the one I specify. – cdarwin Jan 12 '19 at 21:34

How to read an external file list with grunt

1 Answers1