refactor: use node.js api rather than unix commands

package.json

@@ -58,11 +58,10 @@
     "babel:build": "babel src -d js --source-maps -q",
     "babel:watch": "babel src -d js --watch --source-maps",
     "build:respec-w3c-common": "node ./tools/builder.js --profile=w3c-common",
-    "build": "npm run snyk-protect && npm run copydeps && npm run hb:build && npm run highlight:build && npm run babel:build",
+    "build:components": "npm run copydeps && node ./tools/build-components.js && npm run babel:build",
+    "build": "npm run snyk-protect && npm run build:components",
     "copydeps": "node ./tools/copydeps.js",
     "handlebars": "handlebars",
-    "hb:build": "node ./tools/expandpaths.js -a js/*/templates/*.html js/*/templates/*.css js/core/templates/webidl-contiguous/*.html | xargs handlebars -f js/templates.js",
-    "highlight:build": "hljs -n --output js/deps/ xml javascript css http markdown json abnf && mv -f js/deps/highlight.pack.js js/deps/highlight.js",
     "karma": "karma start --single-run",
     "release": "node ./tools/release.js",
     "server": "npm start",

tools/build-components.js

@@ -0,0 +1,22 @@
+const { promisify } = require("util");
+const exec = promisify(require("child_process").exec);
+const move = require("fs-extra").move;
+const glob = require("glob");
+
+(async () => {
+  await buildHandlebars();
+  await buildHighlight();
+})();
+
+async function buildHandlebars() {
+  const paths = ["js/*/templates/*.html", "js/*/templates/*.css", "js/core/templates/webidl-contiguous/*.html"]
+    .map(path => glob.sync(path, { nonull: true }))
+    .reduce((res, file) => res.concat(file), [])
+    .join(" ");
+  await exec(`handlebars ${paths} -a -f js/templates.js`);
+}
+
+async function buildHighlight() {
+  await exec("hljs -n --output js/deps/ xml javascript css http markdown json abnf");
+  await move("js/deps/highlight.pack.js", "js/deps/highlight.js", { overwrite: true });
+}