WIP - add extractor, generate snippet_data

node_modules/gatsby-plugin-offline/get-resources-from-html.js

@@ -0,0 +1,44 @@
+"use strict";
+
+var cheerio = require("cheerio");
+
+var path = require("path");
+
+var fs = require("fs");
+
+var _ = require("lodash");
+
+module.exports = function (htmlPath) {
+  // load index.html to pull scripts/links necessary for proper offline reload
+  var html;
+
+  try {
+    // load index.html to pull scripts/links necessary for proper offline reload
+    html = fs.readFileSync(path.resolve(htmlPath));
+  } catch (err) {
+    // ENOENT means the file doesn't exist, which is to be expected when trying
+    // to open 404.html if the user hasn't created a custom 404 page -- return
+    // an empty array.
+    if (err.code === "ENOENT") {
+      return [];
+    } else {
+      throw err;
+    }
+  } // party like it's 2006
+
+
+  var $ = cheerio.load(html); // holds any paths for scripts and links
+
+  var criticalFilePaths = [];
+  $("\n    script[src],\n    link[as=script],\n    link[as=font],\n    link[as=fetch],\n    link[rel=stylesheet],\n    style[data-href]\n  ").each(function (_, elem) {
+    var $elem = $(elem);
+    var url = $elem.attr("src") || $elem.attr("href") || $elem.attr("data-href"); // Don't cache XML files, or external resources (beginning with // or http)
+
+    var blackListRegex = /(\.xml$|^\/\/|^http)/;
+
+    if (!blackListRegex.test(url)) {
+      criticalFilePaths.push(url.replace(/^\//, ""));
+    }
+  });
+  return _.uniq(criticalFilePaths);
+};