Support Bun with patch changes

lib/constants.ts

@@ -11,6 +11,7 @@ import path from "node:path";
 import fs from "node:fs";
 
 export const BASE_DIR = new URL("..", import.meta.url);
+export const RUNTIME_IDS_WITH_PATCH_VERSIONING = new Set(["bun"]); // List of browsers/runtimes that might add features in patches
 
 /**
  * Tests a specified path to see if it's a local checkout of mdn/browser-compat-data

lib/ua-parser.test.ts

@@ -11,6 +11,7 @@ import {assert} from "chai";
 import {getMajorMinorVersion, parseUA} from "./ua-parser.js";
 
 const browsers = {
+  bun: {name: "Bun", releases: {"1.0.0": {}, "1.1.15": {}, "1.2.0": {}}},
   chrome: {name: "Chrome", releases: {82: {}, 83: {}, 84: {}, 85: {}}},
   chrome_android: {name: "Chrome Android", releases: {85: {}}},
   deno: {name: "Deno", releases: {1.42: {}}},
@@ -522,6 +523,46 @@ describe("parseUA", () => {
     });
   });
 
+  it("Bun 1.0.0 (preserves patch version)", () => {
+    assert.deepEqual(parseUA("!! bun/1.0.0", browsers), {
+      browser: {id: "bun", name: "Bun"},
+      version: "1.0.0",
+      fullVersion: "1.0.0",
+      os: {name: "", version: ""},
+      inBcd: true,
+    });
+  });
+
+  it("Bun 1.1.15 (preserves patch version)", () => {
+    assert.deepEqual(parseUA("!! bun/1.1.15", browsers), {
+      browser: {id: "bun", name: "Bun"},
+      version: "1.1.15",
+      fullVersion: "1.1.15",
+      os: {name: "", version: ""},
+      inBcd: true,
+    });
+  });
+
+  it("Bun 1.2.0 (preserves patch version)", () => {
+    assert.deepEqual(parseUA("!! bun/1.2.0", browsers), {
+      browser: {id: "bun", name: "Bun"},
+      version: "1.2.0",
+      fullVersion: "1.2.0",
+      os: {name: "", version: ""},
+      inBcd: true,
+    });
+  });
+
+  it("Bun 1.1.16 (not in BCD)", () => {
+    assert.deepEqual(parseUA("!! bun/1.1.16", browsers), {
+      browser: {id: "bun", name: "Bun"},
+      version: "1.1.16",
+      fullVersion: "1.1.16",
+      os: {name: "", version: ""},
+      inBcd: false,
+    });
+  });
+
   it("Chrome on iOS (not in BCD)", () => {
     assert.deepEqual(
       parseUA(

lib/ua-parser.ts

@@ -14,6 +14,7 @@ import {
 import {UAParser} from "ua-parser-js";
 
 import type {ParsedUserAgent} from "../types/types.d.ts";
+import {RUNTIME_IDS_WITH_PATCH_VERSIONING} from "./constants.js";
 
 /**
  * Returns the major version from a given version string.
@@ -111,10 +112,11 @@ const parseUA = (userAgent: string, browsers: Browsers): ParsedUserAgent => {
   }
 
   data.fullVersion = data.fullVersion || ua.browser.version || "0";
-  data.version = getMajorMinorVersion(data.fullVersion);
 
-  if (data.browser.id == "bun") {
+  if (RUNTIME_IDS_WITH_PATCH_VERSIONING.has(data.browser.id)) {
     data.version = data.fullVersion;
+  } else {
+    data.version = getMajorMinorVersion(data.fullVersion);
   }
 
   if (!(data.browser.id in browsers)) {
@@ -155,36 +157,46 @@ const parseUA = (userAgent: string, browsers: Browsers): ParsedUserAgent => {
   // with this, find the pair of versions in |versions| that sandwiches
   // |version|, and use the first of this pair. For example, given |version|
   // "10.1" and |versions| entries "10.0" and "10.2", return "10.0".
-  for (let i = 0; i < versions.length - 1; i++) {
-    const current = versions[i];
-    const next = versions[i + 1];
-    if (
-      compareVersions(data.version, current, ">=") &&
-      compareVersions(data.version, next, "<")
-    ) {
+  // However, for Bun, we need exact version matches because patch versions can add features.
+  if (RUNTIME_IDS_WITH_PATCH_VERSIONING.has(data.browser.id)) {
+    // For Bun, only mark as inBcd if exact version exists
+    if (versions.includes(data.version)) {
       data.inBcd = true;
-      data.version = current;
-      break;
+    }
+  } else {
+    for (let i = 0; i < versions.length - 1; i++) {
+      const current = versions[i];
+      const next = versions[i + 1];
+      if (
+        compareVersions(data.version, current, ">=") &&
+        compareVersions(data.version, next, "<")
+      ) {
+        data.inBcd = true;
+        data.version = current;
+        break;
+      }
     }
   }
 
   // We reached the last entry in |versions|. With no |next| to compare against
   // we have to check if it looks like a significant release or not. By default
   // that means a new major version, but for Safari and Samsung Internet the
   // major and minor version are significant.
-  let normalize = getMajorVersion;
-  if (
-    data.browser.id.startsWith("safari") ||
-    data.browser.id === "samsunginternet_android"
-  ) {
-    normalize = getMajorMinorVersion;
-  }
-  if (
-    data.inBcd == false &&
-    normalize(data.version) === normalize(versions[versions.length - 1])
-  ) {
-    data.inBcd = true;
-    data.version = versions[versions.length - 1];
+  if (!RUNTIME_IDS_WITH_PATCH_VERSIONING.has(data.browser.id)) {
+    let normalize = getMajorVersion;
+    if (
+      data.browser.id.startsWith("safari") ||
+      data.browser.id === "samsunginternet_android"
+    ) {
+      normalize = getMajorMinorVersion;
+    }
+    if (
+      data.inBcd == false &&
+      normalize(data.version) === normalize(versions[versions.length - 1])
+    ) {
+      data.inBcd = true;
+      data.version = versions[versions.length - 1];
+    }
   }
 
   return data;

scripts/find-missing-reports.ts

@@ -50,7 +50,7 @@ const generateReportMap = (filter: string) => {
   for (const browser of Object.keys(browsers)) {
     if (
       filter !== "all" &&
-      ["ie", "nodejs", "deno", "oculus"].includes(browser)
+      ["ie", "nodejs", "deno", "bun", "oculus"].includes(browser)
     ) {
       continue;
     }