`inline` and `register` modules options - traceur

Question

What do --modules inline and --modules register options do?
https://github.com/google/traceur-compiler/wiki/Options-for-Compiling.

Answer 1

Using 2ality.com's lib.js example module:
//------ lib.js ------
export const sqrt = Math.sqrt;
export function square(x) {
return x * x;
}
export function diag(x, y) {
return sqrt(square(x) + square(y));
}
//------ main.js ------
import { square, diag } from 'lib';
console.log(square(11)); // 121
console.log(diag(4, 3)); // 5
inline wraps the module in an anonymous function, assigned to an auto-generated variable by the looks, it would be interesting to know what this is all about, the technique can be used to bundle modules without actually using a module system, but the var assigned the object returned would have to be known:
var $__src_47_lib_46_js__ = (function() {
"use strict";
var __moduleName = "src/lib.js";
var sqrt = Math.sqrt;
function square(x) {
return x * x;
}
function diag(x, y) {
return sqrt(square(x) + square(y));
}
return {
get sqrt() {
return sqrt;
},
get square() {
return square;
},
get diag() {
return diag;
}
};
})();
//# sourceMappingURL=lib.js.map
System.register is a draft module format:
System.registerModule("src/lib.js", [], function() {
"use strict";
var __moduleName = "src/lib.js";
var sqrt = Math.sqrt;
function square(x) {
return x * x;
}
function diag(x, y) {
return sqrt(square(x) + square(y));
}
return {
get sqrt() {
return sqrt;
},
get square() {
return square;
},
get diag() {
return diag;
}
};
});
System.get("src/lib.js" + '');
//# sourceMappingURL=lib.js.map
Once the module has been registered, then the System.module( ... ) can be called to load the module. Currently I know traceur (though not the runtime) has the System object polyfilled, presumably also babel.
The System.register format has some useful advantages I would suggest, more than one module can be included in a file which suits a collection of smaller closely coupled modules (typically classes); there is no need to buy in to another module system, e.g., including vanilla JS (test data, shims attached to the global object, etc.) in a node module requires additional boilerplate code adding overhead to the workflow, etc.
The System object though is technology still in development (not included the current draft standard).