Function isOptionalParameter

test/fixtures/snapshot/typescript.js:59547–59567

(node)

            return symbol && withAugmentations ? getMergedSymbol(symbol) : symbol;
        }
        function isOptionalParameter(node) {
            if (ts.hasQuestionToken(node) || isOptionalJSDocPropertyLikeTag(node) || isJSDocOptionalParameter(node)) {
                return true;
            }
            if (node.initializer) {
                var signature = getSignatureFromDeclaration(node.parent);
                var parameterIndex = node.parent.parameters.indexOf(node);
                ts.Debug.assert(parameterIndex >= 0);
                // Only consider syntactic or instantiated parameters as optional, not `void` parameters as this function is used
                // in grammar checks and checking for `void` too early results in parameter types widening too early
                // and causes some noImplicitAny errors to be lost.
                return parameterIndex >= getMinArgumentCount(signature, 1 /* MinArgumentCountFlags.StrongArityForUntypedJS */ | 2 /* MinArgumentCountFlags.VoidIsNonOptional */);
            }
            var iife = ts.getImmediatelyInvokedFunctionExpression(node.parent);
            if (iife) {
                return !node.type &&
                    !node.dotDotDotToken &&
                    node.parent.parameters.indexOf(node) >= iife.arguments.length;
            }
            return false;
        }
        function isOptionalPropertyDeclaration(node) {
            return ts.isPropertyDeclaration(node) && node.questionToken;
        }