From 59951253a4445b04a196b6bad5b7a2f9a3ec0feb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tobias=20H=C3=B8egh?= <tobias@tujo.no>
Date: Tue, 13 Jan 2026 09:05:37 +0100
Subject: [PATCH] feat: add ignoreConditionalChecks setting

Allow reporting inside feature-detection conditionals.

Document the new setting.
---
 README.md            | 13 +++++++++++++
 docs/rules/compat.md |  6 ++++++
 src/helpers.ts       |  5 ++++-
 src/types.ts         |  1 +
 test/e2e.spec.ts     | 16 ++++++++++++++++
 5 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 33ca6b28..f1db05a1 100644
--- a/README.md
+++ b/README.md
@@ -94,6 +94,19 @@ This plugin also supports linting the compatibility of ES APIs in addition to We
 }
 ```
 
+## Conditional Checks
+
+By default, feature detection like `if (fetch) { ... }` does not trigger a
+report. To lint these conditionals anyway, set the following:
+
+```jsonc
+{
+  "settings": {
+    "ignoreConditionalChecks": true,
+  },
+}
+```
+
 ## Configuring for Different Environments
 
 Browserslist allows specifying [different browser queries for multiple environments](https://github.com/browserslist/browserslist#configuring-for-different-environments). By default, this plugin targets the `production` browserslist environment. To change this default, set the `settings.browserslistOpts.env` property in your eslint config:
diff --git a/docs/rules/compat.md b/docs/rules/compat.md
index 51b0b43f..d53e14b8 100644
--- a/docs/rules/compat.md
+++ b/docs/rules/compat.md
@@ -15,3 +15,9 @@ fetch("https://exmaple.com");
 // Using default browser targets
 fetch("https://exmaple.com");
 ```
+
+## Conditional Checks
+
+By default, feature detection like `if (fetch) { ... }` does not trigger a
+report. Set `settings.ignoreConditionalChecks` to `true` to lint these
+conditionals.
diff --git a/src/helpers.ts b/src/helpers.ts
index 3546c331..85ee2942 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -50,7 +50,10 @@ function checkNotInsideIfStatementAndReport(
   sourceCode: SourceCode,
   node: ESLintNode
 ) {
-  if (!isInsideIfStatement(node, sourceCode, context)) {
+  if (
+    context.settings?.ignoreConditionalChecks === true ||
+    !isInsideIfStatement(node, sourceCode, context)
+  ) {
     handleFailingRule(failingRule, node);
   }
 }
diff --git a/src/types.ts b/src/types.ts
index 08a16fe8..d3353fc8 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -79,6 +79,7 @@ export interface Context extends Rule.RuleContext {
     browsers?: Array<string>;
     polyfills?: Array<string>;
     lintAllEsApis?: boolean;
+    ignoreConditionalChecks?: boolean;
     browserslistOpts?: BrowsersListOpts;
   };
 }
diff --git a/test/e2e.spec.ts b/test/e2e.spec.ts
index f89576a6..eb4e80e5 100644
--- a/test/e2e.spec.ts
+++ b/test/e2e.spec.ts
@@ -276,6 +276,22 @@ ruleTester.run("compat", rule, {
     },
   ],
   invalid: [
+    {
+      code: `
+        if (fetch) {
+          fetch()
+        }
+      `,
+      settings: {
+        browsers: ["ExplorerMobile 10"],
+        ignoreConditionalChecks: true,
+      },
+      errors: [
+        {
+          message: "fetch is not supported in IE Mobile 10",
+        },
+      ],
+    },
     {
       code: "window?.fetch?.('example.com')",
       settings: { browsers: ["ie 9"] },