Merge pull request #10 from developit/patch-1

Add support for sites with no routes, and esm output.

Author: vinaypuppal

index.js

@@ -25,16 +25,20 @@ class NetlifyServerPushPlugin {
       let mainJs = '# no js files';
       let mainCss = '# no css files';
 
+      const hasEsm = Object.keys(compilation.assets).filter(filename => /\.esm\.js$/.test(filename)).length !== 0;
+
       for (const filename in compilation.assets) {
         if (!/\.map$/.test(filename)) {
           if (/route-/.test(filename)) {
             routes.push(filename);
-          } else if (/^style(.+)\.css$/.test(filename)) {
+          } else if (/^(style|bundle)(.+)\.css$/.test(filename)) {
             mainCss = `Link: </${filename}>; rel=preload; as=style`;
-          } else if (/^bundle(.+)\.js$/.test(filename)) {
+          } else if (hasEsm && /^bundle(.+)\.esm\.js$/.test(filename)) {
+            mainJs = `Link: </${filename}>; rel=preload; as=script; crossorigin=anonymous`;
+          } else if (!hasEsm && /^bundle(.+)\.js$/.test(filename)) {
             mainJs = `Link: </${filename}>; rel=preload; as=script`;
           }
-        }
+      }
       }
 
       let headers =
@@ -46,6 +50,10 @@ class NetlifyServerPushPlugin {
 
       const redirects = `${this.redirects.join('\n')}\n/* /index.html 200`;
 
+      if (!routes.length) {
+        headers += `\n/*\n\t${mainCss}\n\t${mainJs}`;
+      }
+
       routes.forEach(filename => {
         const path = filename
           .replace(/route-/, '/')