Merge branch 'main' into flat-config-support-core-package

typescript-eslint · Feb 7, 2024 · 8713862 · 8713862
2 parents 69084bd + c298350
commit 8713862
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Showing 2 changed files with 30 additions and 10 deletions.
diff --git a/packages/eslint-plugin/src/rules/prefer-find.ts b/packages/eslint-plugin/src/rules/prefer-find.ts
@@ -125,22 +125,22 @@ export default createRule({
       return isAtLeastOneArrayishComponent;
     }
 
-    function getObjectIfArrayAtExpression(
+    function getObjectIfArrayAtZeroExpression(
       node: TSESTree.CallExpression,
     ): TSESTree.Expression | undefined {
       // .at() should take exactly one argument.
       if (node.arguments.length !== 1) {
         return undefined;
       }
 
-      const atArgument = getStaticValue(node.arguments[0], globalScope);
-      if (atArgument != null && isTreatedAsZeroByArrayAt(atArgument.value)) {
-        const callee = node.callee;
-        if (
-          callee.type === AST_NODE_TYPES.MemberExpression &&
-          !callee.optional &&
-          isStaticMemberAccessOfValue(callee, 'at', globalScope)
-        ) {
+      const callee = node.callee;
+      if (
+        callee.type === AST_NODE_TYPES.MemberExpression &&
+        !callee.optional &&
+        isStaticMemberAccessOfValue(callee, 'at', globalScope)
+      ) {
+        const atArgument = getStaticValue(node.arguments[0], globalScope);
+        if (atArgument != null && isTreatedAsZeroByArrayAt(atArgument.value)) {
           return callee.object;
         }
       }
@@ -153,6 +153,12 @@ export default createRule({
      * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at#parameters
      */
     function isTreatedAsZeroByArrayAt(value: unknown): boolean {
+      // This would cause the number constructor coercion to throw. Other static
+      // values are safe.
+      if (typeof value === 'symbol') {
+        return false;
+      }
+
       const asNumber = Number(value);
 
       if (isNaN(asNumber)) {
@@ -215,7 +221,7 @@ export default createRule({
     return {
       // This query will be used to find things like `filteredResults.at(0)`.
       CallExpression(node): void {
-        const object = getObjectIfArrayAtExpression(node);
+        const object = getObjectIfArrayAtZeroExpression(node);
         if (object) {
           const filterExpression = parseIfArrayFilterExpression(object);
           if (filterExpression) {

diff --git a/packages/eslint-plugin/tests/rules/prefer-find.test.ts b/packages/eslint-plugin/tests/rules/prefer-find.test.ts
@@ -56,6 +56,20 @@ ruleTester.run('prefer-find', rule, {
     "['Just', 'a', 'find'].find(x => x.length > 4);",
     'undefined.filter(x => x)[0];',
     'null?.filter(x => x)[0];',
+    // Should not throw. See https://github.com/typescript-eslint/typescript-eslint/issues/8386
+    `
+      declare function foo(param: any): any;
+      foo(Symbol.for('foo'));
+    `,
+    // Specifically need to test Symbol.for(), not just Symbol(), since only
+    // Symbol.for() creates a static value that the rule inspects.
+    `
+      declare const arr: string[];
+      const s = Symbol.for("Don't throw!");
+      arr.filter(item => item === 'aha').at(s);
+    `,
+    "[1, 2, 3].filter(x => x)[Symbol('0')];",
+    "[1, 2, 3].filter(x => x)[Symbol.for('0')];",
   ],
 
   invalid: [