How can I use grunt-contrib-watch and grunt-contrib-coffee to compile CoffeeScript only as needed?

Question

I'd like to run coffee lint and coffee compile on only the single file that I'm saving. There are hundreds of CoffeeScript files in my project, and compiling all of them takes too much time. Here's my Gruntfile: ``` module.exports = (grunt) -> grunt.initConfig pkg: grunt.file.readJSON 'package.json' coffee: all: expand: true bare: true cwd: 'src/coffeescript/' src: '**/*.coffee' dest: 'public/js/compiled' ext: '.js' coffeelint: all: ['src/coffeescript/**/*.coffee'] watch: coffeescript: files: ['src/**/*.coffee'] tasks: ['coffeelint', 'coffee'] options: spawn: false grunt.event.on 'watch', (action, filepath) -> grunt.config(['coffeelint', 'all'], filepath) grunt.config(['coffee', 'all'], filepath) grunt.loadNpmTasks 'grunt-coffeelint' grunt.loadNpmTasks 'grunt-contrib-coffee' grunt.loadNpmTasks 'grunt-contrib-watch' grunt.registerTask 'default', ['coffeelint', 'coffee', 'watch'] ``` The coffeelint task runs successfully only on the changed file. The coffee compilation doesn't produce a…

Accepted Answer

Try to add something like this to your c task

```
 coffee:
  all:
    filter: (filepath) ->
        fs = require('fs')
        now = new Date()
        modified =  fs.statSync(filepath).mtime
        return (now - modified) < 10000 # or another difference in millyseconds
```

How can I use grunt-contrib-watch and grunt-contrib-coffee to compile CoffeeScript only as needed?

Solution

Problem