use constant

lib/font-face/font-face-proxy.js

@@ -22,6 +22,7 @@
 
 this.fontFaceProxy = this.fontFaceProxy || (() => {
 
+	const NEW_FONT_FACE_EVENT = "single-file-new-font-face";
 	const fontFaces = [];
 
 	if (document instanceof HTMLDocument) {
@@ -29,7 +30,7 @@ this.fontFaceProxy = this.fontFaceProxy || (() => {
 		scriptElement.textContent = `(${hook.toString()})()`;
 		document.documentElement.appendChild(scriptElement);
 		scriptElement.remove();
-		addEventListener("single-file-font-face", event => fontFaces.push(event.detail));
+		addEventListener(NEW_FONT_FACE_EVENT, event => fontFaces.push(event.detail));
 	}
 
 	return {
@@ -58,7 +59,7 @@ this.fontFaceProxy = this.fontFaceProxy || (() => {
 				if (descriptors) {
 					Object.keys(descriptors).forEach(descriptor => detail[FONT_STYLE_PROPERTIES[descriptor]] = descriptors[descriptor]);
 				}
-				dispatchEvent(new CustomEvent("single-file-font-face", { detail }));
+				dispatchEvent(new CustomEvent(NEW_FONT_FACE_EVENT, { detail }));
 				return new FontFace(...argumentsList);
 			}
 		}));