How to use Google's Closure to compile JavaScript

Question

Google just released Closure, which is a compiler to minify JavaScript.

On the product site, it says \"The Closure Compiler has also been integrated with Page Speed\".

Answer 1

The Closure compiler is now available as a JavaScript application. No need for the Java dependency anymore

There are a few ways to integrate with it. I have done it as part of Rollup

ex:

import rollup from 'rollup';
import closure from 'rollup-plugin-closure-compiler-js';

export default {
  entry: 'index.js',
  dest: 'dist/build.js',
  format: 'iife',
  plugins: [
    closure({
      languageIn: 'ECMASCRIPT6',
      languageOut: 'ECMASCRIPT5',
      compilationLevel: 'ADVANCED',
      warningLevel: 'VERBOSE',
      externs: [{src:`
                      var jQuery;
                      jQuery.fadeIn = function() {};  

                      var ko;  
                      ko.applyBindings = function(vm) {};
                      ko.computed = function(a,b) {};
                      ko.observable = function(a) {};
               `}],
    })
  ]
}

More info here:

http://www.syntaxsuccess.com/viewarticle/using-the-closure-compiler---advanced_optimizations