lasso-optimizer

A Babel CodeMod plugin that acts as a build / compile time optimizer for Lasso JS. Gives Lasso JS some extra arms.

What is this?

• Lasso JS produces output bundles similar to the NODEJS common-js style syntax on the browser.
• This is an optimizer stage plugin & a Babel CodeMod for Lasso JS, that is applied on the final aggregated output of Lasso JS.
• It performs code transformations
• It cannot be used as a transform or as a usual JS plugin in the list of Lasso plugins

Why is this needed?

• This plugin helps in further optimizing Lasso JS output bundles under certain conditions, while resolving modules, require.resolve, require, conditional requires & circular dependencies.
• Currrently, Lasso JS inlines the filepaths of modules like

$_mod.def("/marko$4.17.3/components/runtime", function (require, exports, module, __filename, __dirname) {
    const f_55 = require('/marko$4.17.3/components/index-browser.marko');
    exports.a = 45;
    exports.func = () => {};
    module.exports = () => {
   };
});
$_mod_gh_fe.remap("/marko$4.17.3/components", "/marko$4.17.3/components-browser.marko");
$_mod_gh_fe.installed("globalheaderfrontend$25.1.0", "marko", "4.17.3");
$_mod_gh_fe.remap("/marko$4.17.3/src/runtime/components/index", "/marko$4.17.3/src/runtime/components/index-browser");

• While they provide a mirror representation of your projects file system, this tends to be of an overhead & bloat for projects.
• Further, these are resolved on the browser by Lasso Modules Client Side Run Time that performs a Node JS style module resolution.
• Inlined filepaths & the client side runtime take upto >30KB-200KB in your ungzipped output bundle & upto 5KB-20KB in your gzipped response.
• As JS parse times are impacted by bundle size bloats, this helps optimize the bundle for it.

What does this do?

• This plugin applies an output transformation on the final aggregated code / bundle.
• It attempts to resolve all filepaths and module dependencies at build time
• It transform modules into simple function expressions

$_mod.def("/marko$4.17.3/components/runtime", function (require, exports, module, __filename, __dirname) {
    // code here
});
$_mod.run("/marko$4.17.3/components/runtime");
$_mod_gh_fe.remap("/marko$4.17.3/components", "/marko$4.17.3/components-browser.marko");
$_mod_gh_fe.installed("globalheaderfrontend$25.1.0", "marko", "4.17.3");
$_mod_gh_fe.main("/process$4.17.3", "src/runtime/components/index-browser");

to

function __marko_4_17_3__components__runtime(require, exports, module, __filename, __dirname) {
    /* __marko_4_17_3__components_index_browser__marko is already available in toplevel scope */
    const f_55 = require(__marko_4_17_3__components_index_browser__marko);
    exports.a = 45;
    exports.func = () => {};
    module.exports = () => {
   };
}
run(__marko_4_17_3__components__runtime);

• The .remap, .installed, .main, .run, .builtin, resolve, require, def are all resolved at build / asset bundling phase.
• On the browser, the bundle doesn’t have to resolve these anymore.
• By doing this, it gets rid of the Lasso Modules Client Side Run Time & uses a miniature version of it.

What do you get by doing this?

• All inline file paths are resolved before runtime.
• Check out the /sample folder for the input and output. The input is a bundle of size 404KB and copy paste the output bundle into https://try.terser.org/ with options as

{
  toplevel: true,
  compress: {
    toplevel: true
  },
  mangle: {
    toplevel: true
  },
  output: {},
  parse: {},
  rename: {},
}

The minified output will now be 250KB.

Usage

• This cannot be applied as transform in the Lasso config or be used as a plugin.
• This cannot also resolve dynamic require calls where the argument of require is not a String but an identifier resolved dynamically
• The following Lasso Config is a sample where the output would be bundled for production.

  {
    "plugins": [
        "lasso-less",
        "lasso-autoprefixer",
        "lasso-marko",
        "lasso-minify-transpile-inline",
        "rollup-plugin-lasso",
        {
            "plugin": "lasso-inline-slots",
            "config": {
                "inlineSlots": [
                    "inline"
                ]
            }
        }
    ],
    "require": {
        "lastSlot": "inline",
        "transforms": [
            "lasso-babel-env"
        ]
    },
    "outputDir": "static",
    "minify": true,
    "minifyInlineOnly": true,
    "bundlingEnabled": true,
    "resolveCssUrls": true,
    "noConflict": "gh-fe",
    "cacheProfile": "production"
  }

Now, the above output would cause Lasso to dump the final minfied output bundled under
${PROJECT_DIR}/static.

const { readFileSync, writeFileSync } = require('fs');
const { optimizeSingleSourceFile } = require('lasso-optimizer');
const code = readFileSync('static/my-awesome-bundle.js', 'utf8');
const result = optimizeSingleSourceFile(code);
writeFileSync('static/optimized-bundle.js', 'utf8');
// now proceed to upload to resource server.