babel-service demo (tested on Chrome, Chrome Canary and Opera)

On demand targeted transpiling inside the browser's ServiceWorker

Can you add the second default value? + =

Instructions

Take a look at app.js below. Depending on the browser, the code for handling the default parameter will be either transpiled or not. The ServiceWorker running on this page tests the browser support for ES6 default parameters and then either passes through the original source, or transpiles this feature.

Demo source, including screenshots at bahmutov/babel-service-demo and it uses babel-service library inside the ServiceWorker to intercept application code, test ES6 support and selectively transpile.

Source received (via ServiceWorker) for app.js

The code might show add (a, b = 1) if your browser natively supports default parameters. Or it might show transpiled version if browser does not