1 files changed, 197 insertions, 0 deletions
diff --git a/devtools/shared/compatibility/bin/update.js b/devtools/shared/compatibility/bin/update.js
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index 0000000000..f7fbfd2285
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+++ b/devtools/shared/compatibility/bin/update.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/>. */
+
+// The Compatibility panel detects issues by comparing against official MDN compatibility data
+// at https://github.com/mdn/browser-compat-data). It uses a local snapshot of the dataset.
+// This dataset needs to be manually synchronized periodically
+
+// The subsets from the dataset required by the Compatibility panel are:
+// * css.properties: https://github.com/mdn/browser-compat-data/tree/master/css
+
+// The MDN compatibility data is available as a node package ("@mdn/browser-compat-data"),
+// which is used here to update `../dataset/css-properties.json`.
+
+/* eslint-disable mozilla/reject-relative-requires */
+
+"use strict";
+
+const compatData = require("@mdn/browser-compat-data");
+const { properties } = compatData.css;
+
+const { TARGET_BROWSER_ID } = require("../constants.js");
+const { getCompatTable } = require("../helpers.js");
+
+// Flatten all CSS properties aliases here so we don't have to do it at runtime,
+// which is costly.
+flattenAliases(properties);
+parseBrowserVersion(properties);
+removeUnusedData(properties);
+exportData(properties, "css-properties.json");
+
+/**
+ * Builds a list of aliases between CSS properties, like flex and -webkit-flex,
+ * and mutates individual entries in the web compat data store for CSS properties to
+ * add their corresponding aliases.
+ */
+function flattenAliases(compatNode) {
+  for (const term in compatNode) {
+    if (term.startsWith("_")) {
+      // Ignore exploring if the term is _aliasOf or __compat.
+      continue;
+    }
+
+    const compatTable = getCompatTable(compatNode, [term]);
+    if (compatTable) {
+      const aliases = findAliasesFrom(compatTable);
+
+      for (const { alternative_name: name, prefix } of aliases) {
+        const alias = name || prefix + term;
+        compatNode[alias] = { _aliasOf: term };
+      }
+
+      if (aliases.length) {
+        // Make the term accessible as the alias.
+        compatNode[term]._aliasOf = term;
+      }
+    }
+
+    // Flatten deeper node as well.
+    flattenAliases(compatNode[term]);
+  }
+}
+
+function findAliasesFrom(compatTable) {
+  const aliases = [];
+
+  for (const browser in compatTable.support) {
+    let supportStates = compatTable.support[browser] || [];
+    supportStates = Array.isArray(supportStates)
+      ? supportStates
+      : [supportStates];
+
+    for (const { alternative_name: name, prefix } of supportStates) {
+      if (!prefix && !name) {
+        continue;
+      }
+
+      aliases.push({ alternative_name: name, prefix });
+    }
+  }
+
+  return aliases;
+}
+
+function parseBrowserVersion(compatNode) {
+  for (const term in compatNode) {
+    if (term.startsWith("_")) {
+      // Ignore exploring if the term is _aliasOf or __compat.
+      continue;
+    }
+
+    const compatTable = getCompatTable(compatNode, [term]);
+    if (compatTable?.support) {
+      for (const [browserId, supportItem] of Object.entries(
+        compatTable.support
+      )) {
+        // supportItem is an array when there are info for both prefixed and non-prefixed
+        // versions. If it's not an array in the original data, transform it into one
+        // since we'd have to do it in MDNCompatibility at runtime otherwise.
+        if (!Array.isArray(supportItem)) {
+          compatTable.support[browserId] = [supportItem];
+        }
+        for (const item of compatTable.support[browserId]) {
+          replaceVersionsInBrowserSupport(item);
+        }
+      }
+    }
+
+    // Handle deeper node as well.
+    parseBrowserVersion(compatNode[term]);
+  }
+}
+
+function replaceVersionsInBrowserSupport(browserSupport) {
+  browserSupport.added = asFloatVersion(browserSupport.version_added);
+  browserSupport.removed = asFloatVersion(browserSupport.version_removed);
+}
+
+function asFloatVersion(version) {
+  // `version` is not always a string (can be null, or a boolean) and in such case,
+  // we want to keep it that way.
+  if (typeof version !== "string") {
+    return version;
+  }
+
+  if (version.startsWith("\u2264")) {
+    // MDN compatibility data started to use an expression like "≤66" for version.
+    // We just ignore the character here.
+    version = version.substring(1);
+  }
+
+  return parseFloat(version);
+}
+
+/**
+ * Remove all unused data from the file so it's smaller and faster to load
+ */
+function removeUnusedData(compatNode) {
+  for (const term in compatNode) {
+    if (term.startsWith("_")) {
+      // Ignore exploring if the term is _aliasOf or __compat.
+      continue;
+    }
+
+    const compatTable = getCompatTable(compatNode, [term]);
+
+    // source_file references the name of the file in the MDN compat data repo where the
+    // property is handled. We don't make use of it so we can remove it.
+    delete compatTable.source_file;
+    // Not used at the moment. Doesn't seem to have much information anyway
+    delete compatTable.description;
+
+    if (compatTable?.support) {
+      for (const [browserId, supportItem] of Object.entries(
+        compatTable.support
+      )) {
+        // Remove any browser we won't handle
+        if (!TARGET_BROWSER_ID.includes(browserId)) {
+          delete compatTable.support[browserId];
+          continue;
+        }
+
+        // Remove `version_added` and `version_removed`, that are parsed in `replaceVersionsInBrowserSupport`
+        // and which we don't need anymore.
+        for (const item of supportItem) {
+          delete item.version_added;
+          delete item.version_removed;
+          // Those might be interesting, but we're not using them at the moment, so let's
+          // remove them as they can be quite lengthy
+          delete item.notes;
+        }
+      }
+    }
+
+    // Handle deeper node as well.
+    removeUnusedData(compatNode[term]);
+  }
+}
+
+function exportData(data, fileName) {
+  const fs = require("fs");
+  const path = require("path");
+
+  const content = `${JSON.stringify(data)}`;
+
+  fs.writeFile(
+    path.resolve(__dirname, "../dataset", fileName),
+    content,
+    err => {
+      if (err) {
+        console.error(err);
+      } else {
+        console.log(`${fileName} downloaded`);
+      }
+    }
+  );
+}