WIP - add extractor, generate snippet_data

node_modules/gatsby/cache-dir/commonjs/prefetch.js

@@ -0,0 +1,76 @@
+"use strict";
+
+exports.__esModule = true;
+exports.default = void 0;
+
+const support = function (feature) {
+  if (typeof document === `undefined`) {
+    return false;
+  }
+
+  const fakeLink = document.createElement(`link`);
+
+  try {
+    if (fakeLink.relList && typeof fakeLink.relList.supports === `function`) {
+      return fakeLink.relList.supports(feature);
+    }
+  } catch (err) {
+    return false;
+  }
+
+  return false;
+};
+
+const linkPrefetchStrategy = function (url) {
+  return new Promise((resolve, reject) => {
+    if (typeof document === `undefined`) {
+      reject();
+      return;
+    }
+
+    const link = document.createElement(`link`);
+    link.setAttribute(`rel`, `prefetch`);
+    link.setAttribute(`href`, url);
+    link.onload = resolve;
+    link.onerror = reject;
+    const parentElement = document.getElementsByTagName(`head`)[0] || document.getElementsByName(`script`)[0].parentNode;
+    parentElement.appendChild(link);
+  });
+};
+
+const xhrPrefetchStrategy = function (url) {
+  return new Promise((resolve, reject) => {
+    const req = new XMLHttpRequest();
+    req.open(`GET`, url, true);
+
+    req.onload = () => {
+      if (req.status === 200) {
+        resolve();
+      } else {
+        reject();
+      }
+    };
+
+    req.send(null);
+  });
+};
+
+const supportedPrefetchStrategy = support(`prefetch`) ? linkPrefetchStrategy : xhrPrefetchStrategy;
+const preFetched = {};
+
+const prefetch = function (url) {
+  return new Promise(resolve => {
+    if (preFetched[url]) {
+      resolve();
+      return;
+    }
+
+    supportedPrefetchStrategy(url).then(() => {
+      resolve();
+      preFetched[url] = true;
+    }).catch(() => {}); // 404s are logged to the console anyway
+  });
+};
+
+var _default = prefetch;
+exports.default = _default;