Microfill

Only loads polyfills for the missing gabs.

How does it work

Microfill replaces your javascript file with a file that looks like this:

;(function(){
    var n = 0;
 
    if (!window.setImmediate) n += 1 << 0;
    if (!window.Promise) n += 1 << 1;
    if (!window.fetch) n += 1 << 2;
    if (!window.WeakMap || !window.Map || !window.Set) n += 1 << 3;
 
    var script = document.createElement("script");
    script.src = "file-" + n.toString(16) + ".js";
    script.type = "text/javascript";
    document.head.appendChild(script);
})();

If a feature is missing, n will be increased by a certain value. Based on the final value of n a file will be loaded. Microfill generates such file for every possible combination of polyfills that are needed. See the test directory for a sample output.

How to use

Using node.js

var microfill = require('microfill');
 
microfill.compile(
    'lib/script.js', // Input
    'dist/script.js', // Output
    'script.js', // Filename that will be used in the compiled file
    ['set-immediate', 'promise', 'fetch', 'collections'] // Polyfills
);

Using gulp

Use gulp-microfill.

var gulp = require('gulp');
var microfill = require('gulp-microfill');
 
gulp.task('default', function() {
    gulp.src('lib/**/*.js')
        .pipe(microfill(['set-immediate', 'promise', 'fetch', 'collection']))
        .pipe(gulp.dest('release'))
});

Supported polyfills

• set-immediate
• promise
• fetch
• collections (WeapMap, Map, Set)

License

MIT