How to use the spec.protoToAssign transformer.
The protoToAssign optional transformer will transform all __proto__
assignments to a method that will do a shallow copy of all properties.
This means that the following will work:
var foo = { a: 1 };
var bar = { b: 2 };
bar.__proto__ = foo;
bar.a; // 1
bar.b; // 2
however the following will not:
var foo = { a: 1 };
var bar = { b: 2 };
bar.__proto__ = foo;
bar.a; // 1
foo.a = 2;
bar.a; // 1 - should be 2 but remember that nothing is bound and it's a straight copy
This is a case that you have to be aware of if you intend to use this transformer.
require("babel").transform("code", { optional: ["spec.protoToAssign"] });
$ babel --optional spec.protoToAssign script.js
In
bar.__proto__ = foo;
Out
var _defaults = ...;
_defaults(bar, foo);