I was able to get this working with React Helmet.
I add the dmloader.js and the engine setup / initialization script tags dynamically. React Helmet will always execute async so I added a bit of extra code to make sure my initialization doesn’t run until after dmloader.js has loaded.
const DefoldRuntime = ({ dimensions }) => {
const { width, height } = dimensions;
useEffect(() => {
document.getElementById('canvas').width = width;
document.getElementById('canvas').height = height;
}, [width, height]);
return (
<div style={{ alignItems: 'center', justifyContent: 'center', overflow: 'hidden' }}>
<canvas id="canvas" width={width} height={height} style={{
backgroundColor: '#333333',
backgroundRepeat: 'no-repeat',
backgroundPosition: 'center center',
backgroundSize: '70%',
backgroundImage: `url("data:image/svg+xml,%3C%3Fxml version='1.0' encoding='utf-8'%3F%3E%3Csvg version='1.1' id='Layer_1' xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' x='0px' y='0px' width='300px' height='64px' viewBox='-2467.5 2469 300 64' style='enable-background:new -2467.5 2469 300 64;' xml:space='preserve'%3E%3Cstyle type='text/css'%3E .st0%7Bfill:%2315244A;%7D .st1%7Bfill:url(%23SVGID_1_);%7D .st2%7Bfill:url(%23SVGID_2_);%7D%0A%3C/style%3E%3Ctitle%3Edefold-logo-html5-splash%3C/title%3E%3Cpolygon class='st0' points='-2177,2482.9 -2175.5,2482.9 -2175.5,2486.7 -2174.4,2486.7 -2174.4,2482.9 -2173.2,2482.9 -2173.2,2481.9 -2177,2481.9 '/%3E%3Cpolygon class='st0' points='-2169.8,2484.1 -2171,2482.1 -2172.1,2482.1 -2172.1,2486.7 -2171,2486.7 -2171,2483.5 -2169.7,2485.6 -2169.7,2485.6 -2168.5,2483.5 -2168.5,2486.7 -2167.5,2486.7 -2167.5,2482.1 -2168.6,2482.1 '/%3E%3Cpath class='st0' d='M-2376,2482h-13.8v38h13.6c6.6,0,12.2-1.9,16.1-5.5c3.8-3.5,5.8-8.5,5.7-13.7v-0.1 C-2354.5,2489.3-2362.9,2482-2376,2482z M-2364,2501.2c0,6.7-4.5,10.9-11.8,10.9h-4.7v-22h4.7c7.3,0,11.8,4.2,11.8,10.9 L-2364,2501.2z'/%3E%3Cpolygon class='st0' points='-2340.9,2505 -2325.1,2505 -2325.1,2497.4 -2340.9,2497.4 -2340.9,2489.6 -2322.4,2489.6 -2322.4,2481.9 -2350.1,2481.9 -2350.1,2520 -2322.2,2520 -2322.2,2512.4 -2340.9,2512.4 '/%3E%3Cpolygon class='st0' points='-2317.1,2481.9 -2317.1,2520 -2307.9,2520 -2307.9,2505.9 -2293,2505.9 -2293,2498.4 -2307.9,2498.4 -2307.9,2489.9 -2289.6,2489.9 -2289.6,2481.9 '/%3E%3Cpolygon class='st0' points='-2233,2482.1 -2242.2,2482.1 -2242.2,2520 -2216.3,2520 -2216.3,2512.2 -2233,2512.2 '/%3E%3Cpath class='st0' d='M-2197.1,2482h-13.7v38h13.5c6.7,0,12.2-1.9,16.1-5.5c3.8-3.5,5.8-8.5,5.7-13.7v-0.1 C-2175.5,2489.3-2184,2482-2197.1,2482z M-2185.1,2501.2c0,6.7-4.5,10.9-11.8,10.9h-4.7v-22h4.7c7.3,0,11.8,4.2,11.8,10.9V2501.2z' /%3E%3Cpath class='st0' d='M-2267.5,2481.7c-10.8,0-19.6,8.8-19.6,19.7c0,10.8,8.8,19.6,19.7,19.6c10.8,0,19.6-8.8,19.6-19.6l0,0 C-2247.8,2490.5-2256.6,2481.7-2267.5,2481.7C-2267.5,2481.7-2267.5,2481.7-2267.5,2481.7z M-2258,2507.9l-8.8,5.1 c-0.5,0.3-1.2,0.3-1.8,0l-8.8-5.1c-0.5-0.3-0.9-0.9-0.9-1.5v-10.2c0-0.6,0.3-1.2,0.9-1.5l8.8-5.1c0.5-0.3,1.2-0.3,1.8,0l8.8,5.1 c0.5,0.3,0.9,0.9,0.9,1.5v10.2C-2257.1,2507-2257.4,2507.6-2258,2507.9z'/%3E%3Cpath class='st0' d='M-2423.2,2494.6l-11.1,6.4l-11.1-6.4l11.1-6.4L-2423.2,2494.6z M-2412.1,2501v12.8l11.1-6.4L-2412.1,2501z M-2467.5,2507.4l11.1,6.4V2501L-2467.5,2507.4z M-2434.3,2526.6l11.1,6.4l11.1-6.4l-11.1-6.4l11.1-6.4l-11.1-6.4l-11.1,6.4 l-11.1-6.4l-11.1,6.4l11.1,6.4l-11.1,6.4l11.1,6.4L-2434.3,2526.6z'/%3E%3ClinearGradient id='SVGID_1_' gradientUnits='userSpaceOnUse' x1='-2451.2178' y1='2525.4604' x2='-2406.2178' y2='2499.6304' gradientTransform='matrix(1 0 0 -1 0 5004)'%3E%3Cstop offset='0' style='stop-color:%231C68EC'/%3E%3Cstop offset='1' style='stop-color:%2300E9DF'/%3E%3C/linearGradient%3E%3Cpath class='st1' d='M-2412.1,2513.8v12.8l-11.1-6.4L-2412.1,2513.8z M-2434.3,2513.8V2501l-11.1-6.4v12.8L-2434.3,2513.8z M-2445.4,2469v12.8l11.1-6.4L-2445.4,2469z M-2412.1,2488.2L-2412.1,2488.2 M-2423.2,2507.4l11.1,6.4V2501l11.1,6.4v-12.8 l-11.1-6.4v-12.8l0,0l-11.1-6.4v12.8l-11.1-6.4v12.8l11.1,6.4V2507.4z'/%3E%3ClinearGradient id='SVGID_2_' gradientUnits='userSpaceOnUse' x1='-2465.9385' y1='2521.2493' x2='-2423.5085' y2='2496.7893' gradientTransform='matrix(1 0 0 -1 0 5004)'%3E%3Cstop offset='0' style='stop-color:%23FF3C2A'/%3E%3Cstop offset='1' style='stop-color:%23FFD215'/%3E%3C/linearGradient%3E%3Cpath class='st2' d='M-2434.3,2513.8V2501l11.1-6.4v12.8L-2434.3,2513.8z M-2434.3,2475.4l11.1,6.4V2469L-2434.3,2475.4z M-2456.5,2488.2L-2456.5,2488.2 M-2445.4,2494.6l11.1-6.4v-12.8l-11.1,6.4V2469l-11.1,6.4l0,0v12.8l-11.1,6.4v12.8l11.1-6.4v12.8 l11.1-6.4V2494.6z M-2456.5,2513.8v12.8l11.1-6.4L-2456.5,2513.8z'/%3E%3C/svg%3E%0A")`
}}></canvas>
<Helmet>
<script id='engine-loader' type='text/javascript' src="/assets/dmloader.js"></script>
<script id='engine-setup' type='text/javascript'>{`
function loadDefold() {
var Module = window.Module;
if (Module) {
var extra_params = {
archive_location_filter: function( path ) {
return ("/assets/archive" + path + "");
},
engine_arguments: [],
custom_heap_size: 268435456,
disable_context_menu: true
}
Module['onRuntimeInitialized'] = function() {
Module.runApp("canvas", extra_params);
};
Module["locateFile"] = function(path, scriptDirectory)
{
// dmengine*.wasm is hardcoded in the built JS loader for WASM,
// we need to replace it here with the correct project name.
if (path == "dmengine.wasm" || path == "dmengine_release.wasm" || path == "dmengine_headless.wasm") {
path = "tsdtemplate.wasm";
}
return scriptDirectory + path;
};
EngineLoader.load("canvas", "/assets/tsdtemplate");
}
else {
setTimeout(loadDefold, 100);
}
}
loadDefold();
`}</script>
</Helmet>
</div>
);
}