pkg/dart2wasm/bin/wasm_runner.html

<!-- Specify wasm filename prefix in URL query parameter 'name'. Default is 'main.dart' -->
<!-- Example: http://localhost:8080/wasm_runner.html?name=myapp -->

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta charset="utf-8">
</head>
<style>body {background-color: black}</style>
<body>
  <script type="module">
    let filename = (new URLSearchParams(window.location.search)).get('name') ?? 'main.dart';
    let mjs = await import(`./${filename}.mjs`);
    let compiledApp = await mjs.compileStreaming(fetch(`${filename}.wasm`));

    function loadDeferredModules(modules, callback) {
        return Promise.all(modules.map((m) => callback(m, fetch(m))));
    }

    let idMap;
    async function loadIdMap() {
        const jsonRes = await fetch(`${filename}.json`);
        const allJson = await jsonRes.json();
        const map = {};
        for (const val of Object.values(allJson)) {
            const imports = val["imports"];
            for (const id of Object.keys(imports)) {
                map[id] = imports[id];
            }
        }
        return map;
    }
    async function loadDeferredId(id, callback) {
        idMap ??= await loadIdMap();
        return loadDeferredModules(idMap[id], callback);
    }
    let instantiatedModule = await compiledApp.instantiate({}, {
        loadDeferredModules: loadDeferredModules,
        loadDeferredId: loadDeferredId,
    });

    instantiatedModule.invokeMain();
  </script>
</body>
</html>