How to use the less-plugin-clean-css with grunt-contrib-less?

Question

I am trying to use less-plugin-clean-css with grunt-contrib-less but I am unable to get it to run. It seems the grunt configuration can't find or install the plugin. This is for a fork of bootstrap that I maintain.

I have updated the Gruntfile.js with:

grunt.initConfig({
...
less: {
  compileCore: {
    options: {
      strictMath: true,
      sourceMap: true,
      outputSourceFiles: true,
   +  plugins: [
   +    (new require('less-plugin-clean-css')({
   +      "advanced": true,
   +      "compatibility": "ie8"
   +    }))
   +   ],
      sourceMapURL: '<%= pkg.name %>.css.map',
      sourceMapFilename: 'dist/css/<%= pkg.name %>.css.map'
    },
    src: 'less/bootstrap.less',
    dest: 'dist/css/<%= pkg.name %>.css'
  ...
  }
},

Installed the plugin:

npm install less-plugin-clean-css --save-dev

Run grunt and get this error:

Running "less:compileCore" (less) task
>> TypeError: Cannot read property 'install' of undefined

What am I missing?

Answer 1

The correct syntax needs additional parentheses around require:

plugins: [
    (new (require('less-plugin-clean-css'))({
        advanced: true,
        compatibility: 'ie8'
    }))
]