marko-lazy

A simple lazy loader for marko components that will only load the component when it's in view
To use: npm install marko-lazy
Create a lazy-renderers.js file at your project root that looks something like this:

export default async function (componentName) {
  switch (componentName) {
    case "myAwesomeWidget":
      return await import("./path/to/myAwesomeWidget.marko"); //client side rendering is better for complex items with state
    case "myAwesomeWidget2":
      return "/path/to/ssr/of/myAwesomeWidget2.marko"; //server side rendering is better for simple items
  }
}

Then, inside a marko file you can use it like this:
lazy-loader component="myAwesomeWidget" model={foo:"bar"}

@skeleton (optional)

If you want a placeholder loading widget to display you can supply a skeleton like this:

lazy-loader component="myAwesomeWidget" model={foo:"bar"}
    @skeleton
        div -- loading...

renderMethod (optional)

Alternatively you can use the renderMethod prop to pass in a function that resolves to the component. (Note: this may not work as expected in the root component)

$ let renderMethod = async () => {
  return await import('./path/to/myAwesomeWidget.marko')
}
lazy-loader component="myAwesomeWidget" model={foo:"bar"} renderMethod=renderMethod
  @skeleton
    div -- loading...

enhanceModel (optional)

Pass a url to the enhanceModel property to have the lazy-loader fetch data from your server that gets appended to the model before attempting to render it.

lazy-loader component="myAwesomeWidget" model={foo:"bar"} enhanceModel="/path/to/data"

customLoadEvent (optional)

If the customLoadEvent property is set, then view-based lazy loading will be disabled and it will instead attach a listener to the custom load event.
Example:

lazy-loader component="pop-up" customLoadEvent="myFormSubmit" model={foo:"bar"}

//^that would only render when the myFormSubmit event is fired elsewhere in code like this:

document.dispatchEvent(new CustomEvent("myFormSubmit"));

vite config note

To allow lazy loaded components to hot-reload, exclude marko-lazy from the optimized dependency list in your vite config.

import { defineConfig } from "vite";
export default defineConfig({
    ...
    optimizeDeps: {
        exclude: ["marko-lazy"],
    }
});

example code for server-side rendering of a single marko component in express

import icon from '../path/to/icon.marko'
const lazyComponents = {
    "icon":icon
}
export const getHTMLComponent = async(req,res)=>{
  let model = req.body || {};
	let componentName = String(req.params.componentName).replace(/[^0-9A-Za-z\-\_\/\?\.]/g,'');
    if(typeof lazyComponents[componentName] == "undefined") return res.json({error:"invalid component"});
    let html = await new Promise((resolve) => {
        lazyComponents[componentName].renderToString(model, (err, result) => {
            if(err) console.log(err);
            resolve(result)
        });
    });
    res.set('Content-Type', 'text/html');
    res.send(html);
}

note:
this project seemed to work best with node v18, your mileage may vary with older node versions.