Update: improve use-isnan rule to detect Number.NaN (fixes #14715) (#…

…14718) * Update: improve `isNaNIdentifier` to detect `Number.isNaN` (fixes #14715) * Chore: add test cases for `Number.NaN` * Docs: add more examples for `use-isnan` * Chore: improve logic and add more test cases * Docs: Update docs/rules/use-isnan.md Co-authored-by: Milos Djermanovic <[email protected]> Co-authored-by: Milos Djermanovic <[email protected]>
eslint · Jun 26, 2021 · 104c0b5 · 104c0b5
1 parent b08170b
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diff --git a/docs/rules/use-isnan.md b/docs/rules/use-isnan.md
@@ -25,6 +25,14 @@ if (foo == NaN) {
 if (foo != NaN) {
     // ...
 }
+
+if (foo == Number.NaN) {
+    // ...
+}
+
+if (foo != Number.NaN) {
+    // ...
+}
 ```
 
 Examples of **correct** code for this rule:
@@ -77,6 +85,26 @@ switch (NaN) {
         break;
     // ...
 }
+
+switch (foo) {
+    case Number.NaN:
+        bar();
+        break;
+    case 1:
+        baz();
+        break;
+    // ...
+}
+
+switch (Number.NaN) {
+    case a:
+        bar();
+        break;
+    case b:
+        baz();
+        break;
+    // ...
+}
 ```
 
 Examples of **correct** code for this rule with `"enforceForSwitchCase"` option set to `true` (default):
@@ -126,6 +154,26 @@ switch (NaN) {
         break;
     // ...
 }
+
+switch (foo) {
+    case Number.NaN:
+        bar();
+        break;
+    case 1:
+        baz();
+        break;
+    // ...
+}
+
+switch (Number.NaN) {
+    case a:
+        bar();
+        break;
+    case b:
+        baz();
+        break;
+    // ...
+}
 ```
 
 ### enforceForIndexOf

diff --git a/lib/rules/use-isnan.js b/lib/rules/use-isnan.js
@@ -21,7 +21,10 @@ const astUtils = require("./utils/ast-utils");
  * @returns {boolean} `true` if the node is 'NaN' identifier.
  */
 function isNaNIdentifier(node) {
-    return Boolean(node) && node.type === "Identifier" && node.name === "NaN";
+    return Boolean(node) && (
+        astUtils.isSpecificId(node, "NaN") ||
+        astUtils.isSpecificMemberAccess(node, "Number", "NaN")
+    );
 }
 
 //------------------------------------------------------------------------------