change to typescript, fix drawing regression

eleventy.config.js

@@ -15,9 +15,9 @@ module.exports = config => {
 		esbuild.build({
 			entryPoints: [
 				`${input}/style.css`,
-				`${input}/bytebeat.js`,
+				`${input}/bytebeat.ts`,
+				`${input}/audio-worklet.ts`,
 				`${input}/embed.ts`,
-				`${input}/audio-worklet.js`,
 			],
 			outdir: output,
 			format: "esm",

src/bytebeat.ts

@@ -545,7 +545,9 @@ const bytebeat = Object.seal({
 						imagePos,
 					width,
 				);
-				initCallback(startX);
+				if (initCallback) {
+					initCallback(startX);
+				}
 				for (let xPos = startX; xPos !== endX; xPos = this.fmod(xPos + 1, width)) {
 					callback(xPos, false);
 				}

src/index.pug

@@ -8,8 +8,8 @@ html(lang="en")
 		title Bytebeat composer
 		link(href="/favicon.png" rel="shortcut icon")
 		link(href="/style.css" type="text/css" rel="stylesheet")
-		link(rel="modulepreload" as="audioworklet" href="/audio-worklet.js")
 		script(src="/bytebeat.js" async type="module")
+		link(rel="modulepreload" as="audioworklet" href="/audio-worklet.js")
 	body
 		main#content
 			section.container-fixed