1 files changed, 112 insertions, 0 deletions
diff --git a/devtools/shared/compatibility/helpers.js b/devtools/shared/compatibility/helpers.js
new file mode 100644
index 0000000000..d69e92a929
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+++ b/devtools/shared/compatibility/helpers.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+// This file might be required from a node script (./bin/update.js), so don't use
+// Chrome API here.
+
+/**
+ * Return the compatibility table from given compatNode and specified terms.
+ * For example, if the terms is ["background-color"],
+ * this function returns compatNode["background-color"].__compat.
+ *
+ * @return {Object} compatibility table
+ *   {
+ *     description: {String} Description of this compatibility table.
+ *     mdn_url: {String} Document in the MDN.
+ *     support: {
+ *       $browserName: {String} $browserName is such as firefox, firefox_android and so on.
+ *         [
+ *           {
+ *              added: {String}
+ *                The version this feature was added.
+ *              removed: {String} Optional.
+ *                The version this feature was removed. Optional.
+ *              prefix: {String} Optional.
+ *                The prefix this feature is needed such as "-moz-".
+ *              alternative_name: {String} Optional.
+ *                The alternative name of this feature such as "-moz-osx-font-smoothing" of "font-smooth".
+ *              notes: {String} Optional.
+ *                A simple note for this support.
+ *           },
+ *           ...
+ *         ],
+ *    },
+ *    status: {
+ *      experimental: {Boolean} If true, this feature is experimental.
+ *      standard_track: {Boolean}, If true, this feature is on the standard track.
+ *      deprecated: {Boolean} If true, this feature is deprecated.
+ *    }
+ *  }
+ */
+function getCompatTable(compatNode, terms) {
+  let targetNode = getCompatNode(compatNode, terms);
+
+  if (!targetNode) {
+    return null;
+  }
+
+  if (!targetNode.__compat) {
+    for (const field in targetNode) {
+      // TODO: We don't have a way to know the context for now.
+      // Thus, use first context node as the compat table.
+      // e.g. flex_context of align-item
+      // https://github.com/mdn/browser-compat-data/blob/master/css/properties/align-items.json#L5
+      if (field.endsWith("_context")) {
+        targetNode = targetNode[field];
+        break;
+      }
+    }
+  }
+
+  return targetNode.__compat;
+}
+
+/**
+ * Return a compatibility node which is target for `terms` parameter from `compatNode`
+ * parameter. For example, when check `background-clip:  content-box;`, the `terms` will
+ * be ["background-clip", "content-box"]. Then, follow the name of terms from the
+ * compatNode node, return the target node. Although this function actually do more
+ * complex a bit, if it says simply, returns a node of
+ * compatNode["background-clip"]["content-box""] .
+ */
+function getCompatNode(compatNode, terms) {
+  for (const term of terms) {
+    compatNode = getChildCompatNode(compatNode, term);
+    if (!compatNode) {
+      return null;
+    }
+  }
+
+  return compatNode;
+}
+
+function getChildCompatNode(compatNode, term) {
+  term = term.toLowerCase();
+
+  let child = null;
+  for (const field in compatNode) {
+    if (field.toLowerCase() === term) {
+      child = compatNode[field];
+      break;
+    }
+  }
+
+  if (!child) {
+    return null;
+  }
+
+  if (child._aliasOf) {
+    // If the node is an alias, returns the node the alias points.
+    child = compatNode[child._aliasOf];
+  }
+
+  return child;
+}
+
+module.exports = {
+  getCompatNode,
+  getCompatTable,
+};