navigationBar/Tree: Better description for anonymous function (#27063)

src/services/navigationBar.ts

@@ -631,28 +631,50 @@ namespace ts.NavigationBar {
     }
 
     function getFunctionOrClassName(node: FunctionExpression | FunctionDeclaration | ArrowFunction | ClassLikeDeclaration): string {
+        const { parent } = node;
         if (node.name && getFullWidth(node.name) > 0) {
             return declarationNameToString(node.name);
         }
         // See if it is a var initializer. If so, use the var name.
-        else if (node.parent.kind === SyntaxKind.VariableDeclaration) {
-            return declarationNameToString((node.parent as VariableDeclaration).name);
+        else if (isVariableDeclaration(parent)) {
+            return declarationNameToString(parent.name);
         }
         // See if it is of the form "<expr> = function(){...}". If so, use the text from the left-hand side.
-        else if (node.parent.kind === SyntaxKind.BinaryExpression &&
-            (node.parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) {
-            return nodeText((node.parent as BinaryExpression).left).replace(whiteSpaceRegex, "");
+        else if (isBinaryExpression(parent) && parent.operatorToken.kind === SyntaxKind.EqualsToken) {
+            return nodeText(parent.left).replace(whiteSpaceRegex, "");
         }
         // See if it is a property assignment, and if so use the property name
-        else if (node.parent.kind === SyntaxKind.PropertyAssignment && (node.parent as PropertyAssignment).name) {
-            return nodeText((node.parent as PropertyAssignment).name);
+        else if (isPropertyAssignment(parent)) {
+            return nodeText(parent.name);
         }
         // Default exports are named "default"
         else if (getModifierFlags(node) & ModifierFlags.Default) {
             return "default";
         }
+        else if (isClassLike(node)) {
+            return "<class>";
+        }
+        else if (isCallExpression(parent)) {
+            const name = getCalledExpressionName(parent.expression);
+            if (name !== undefined) {
+                const args = mapDefined(parent.arguments, a => isStringLiteral(a) ? a.getText(curSourceFile) : undefined).join(", ");
+                return `${name}(${args}) callback`;
+            }
+        }
+        return "<function>";
+    }
+
+    function getCalledExpressionName(expr: Expression): string | undefined {
+        if (isIdentifier(expr)) {
+            return expr.text;
+        }
+        else if (isPropertyAccessExpression(expr)) {
+            const left = getCalledExpressionName(expr.expression);
+            const right = expr.name.text;
+            return left === undefined ? right : `${left}.${right}`;
+        }
         else {
-            return isClassLike(node) ? "<class>" : "<function>";
+            return undefined;
         }
     }
 

tests/cases/fourslash/navigationBarAnonymousClassAndFunctionExpressions.ts

@@ -18,6 +18,8 @@
 ////    // These will only show up as childItems.
 ////    function z() {}
 ////    console.log(function() {})
+////    describe("this", 'function', () => {});
+////    [].map(() => {});
 ////})
 ////(function classes() {
 ////    // Classes show up in top-level regardless of whether they have names or inner declarations.
@@ -71,7 +73,15 @@ verify.navigationTree({
             "kind": "function",
             "childItems": [
                 {
-                    "text": "<function>",
+                    "text": "console.log() callback",
+                    "kind": "function"
+                },
+                {
+                    "text": `describe("this", 'function') callback`,
+                    "kind": "function"
+                },
+                {
+                    "text": `map() callback`,
                     "kind": "function"
                 },
                 {
@@ -185,7 +195,15 @@ verify.navigationBar([
         "kind": "function",
         "childItems": [
             {
-                "text": "<function>",
+                "text": "console.log() callback",
+                "kind": "function"
+            },
+            {
+                "text": `describe("this", 'function') callback`,
+                "kind": "function"
+            },
+            {
+                "text": `map() callback`,
                 "kind": "function"
             },
             {