JSM to ES Module Babel Plugin


This module converts import and export statements in .jsm modules to ES modules. For example:

Source:

``js
const {utils: Cu} = Components;
const {Bar, Baz} = Cu.import("resource://activity-stream/addon/barbaz.jsm", {});

function Stuff() {
return 123;
}

this.Whatever = {};
this.Stuff = Stuff;
var EXPORTED_SYMBOLS = ["Stuff", "Whatever"];
`

Compiles to:

`js
import {Bar, Baz} from "addon/barbaz.js";

export function Stuff() {
return 123;
}

export var Whatever = {};
`

Caveats / Limitations

$3

Because import and export statements in ES modules must be statically analyzable, this plugin will only transform
top level Cu.import / EXPORTED_SYMBOLS. Example:

Good:

`js
const {utils: Cu} = Components;
const {Bar} = Cu.import("resource://foo/Bar.jsm", {});

this.Baz = 123;
this.EXPORTED_SYMBOLS = ["Baz"];
`

Bad:

`js
const {utils: Cu} = Components;
const root = this;
function innerFunction() {
// This won't get converted because it's inside innerFunction
const {Bar} = Cu.import("resource://foo/Bar.jsm", {});

// Don't do this either
root.Baz = 123;
}

var EXPORTED_SYMBOLS = ["Baz"];
`

$3

You should only declare this.EXPORTED_SYMBOLS once in the top-level scope, and it should not be modified.

Good:

`js
function Foo() {...}
this.Foo = Foo;
this.Bar = 123;
this.EXPORTED_SYMBOLS = ["Foo", "Bar"];
`

Bad:

`js
const root = this;
const Foo = 123;
root.EXPORTED_SYMBOLS = ["Foo"]; // Don't alias this when exporting
root.Bar = 456;
root.EXPORTED_SYMBOLS.push("Bar"); // Don't do this

`

$3

Assigning variables to Components or Components.utils is OK, but don't assign the .import;

`js
const C = Components; // OK
const {utils: Cu} = Components; // OK
const u = Components.utils // OK

const {import} = Cu; // Don't do this
const i = Components.utils.import // Don't do this

`

Options

$3

Defaults to /^resource:\/\/. A RegEx or String that tests for which import paths to rewrite.

$3

Defaults to false. Remove the basePath component of the import string?

e.g. If the basePath is /^resource:\/\/, resource://activity-stream/foo.js will be rewritten to activity-stream/foo.js.

`
"plugins": ["transform-react-jsx", {basePath: "resource://activity-stream/"}],
`

$3

Defaults to false`. Should we remove non-matching imports?