Filter out private fields in string literal property completions.

Also some minor simplifications.

Fixes 36082.

src/services/completions.ts

@@ -403,8 +403,8 @@ namespace ts.Completions {
             kindModifiers: SymbolDisplay.getSymbolModifiers(symbol),
             sortText,
             source: getSourceFromOrigin(origin),
-            hasAction: trueOrUndefined(!!origin && originIsExport(origin)),
-            isRecommended: trueOrUndefined(isRecommendedCompletionMatch(symbol, recommendedCompletion, typeChecker)),
+            hasAction: origin && originIsExport(origin) || undefined,
+            isRecommended: isRecommendedCompletionMatch(symbol, recommendedCompletion, typeChecker) || undefined,
             insertText,
             replacementSpan,
         };
@@ -415,10 +415,6 @@ namespace ts.Completions {
             !!(localSymbol.flags & SymbolFlags.ExportValue) && checker.getExportSymbolOfSymbol(localSymbol) === recommendedCompletion;
     }
 
-    function trueOrUndefined(b: boolean): true | undefined {
-        return b ? true : undefined;
-    }
-
     function getSourceFromOrigin(origin: SymbolOriginInfo | undefined): string | undefined {
         return origin && originIsExport(origin) ? stripQuotes(origin.moduleSymbol.name) : undefined;
     }

src/services/stringCompletions.ts

@@ -6,9 +6,9 @@ namespace ts.Completions.StringCompletions {
             return entries && convertPathCompletions(entries);
         }
         if (isInString(sourceFile, position, contextToken)) {
-            return !contextToken || !isStringLiteralLike(contextToken)
-                ? undefined
-                : convertStringLiteralCompletions(getStringLiteralCompletionEntries(sourceFile, contextToken, position, checker, options, host), sourceFile, checker, log, preferences);
+            if (!contextToken || !isStringLiteralLike(contextToken)) return undefined;
+            const entries = getStringLiteralCompletionEntries(sourceFile, contextToken, position, checker, options, host);
+            return convertStringLiteralCompletions(entries, sourceFile, checker, log, preferences);
         }
     }
 
@@ -214,7 +214,11 @@ namespace ts.Completions.StringCompletions {
     }
 
     function stringLiteralCompletionsFromProperties(type: Type | undefined): StringLiteralCompletionsFromProperties | undefined {
-        return type && { kind: StringLiteralCompletionKind.Properties, symbols: type.getApparentProperties(), hasIndexSignature: hasIndexSignature(type) };
+        return type && {
+            kind: StringLiteralCompletionKind.Properties,
+            symbols: type.getApparentProperties().filter(prop => !isPrivateIdentifierPropertyDeclaration(prop.valueDeclaration)),
+            hasIndexSignature: hasIndexSignature(type)
+        };
     }
 
     function getStringLiteralTypes(type: Type | undefined, uniques = createMap<true>()): readonly StringLiteralType[] {

tests/cases/fourslash/getJavaScriptCompletions21.ts

@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts" />
+
+// @allowNonTsExtensions: true
+// @Filename: file.js
+
+////class Prv {
+////    #privatething = 1;
+////    notSoPrivate = 1;
+////}
+////new Prv()['/**/'];
+
+verify.completions({
+    marker: "",
+    exact: ["notSoPrivate"]
+});