Function narrowTypeByInstanceof

test/fixtures/snapshot/typescript.js:71241–71280

(type, expr, assumeTrue)

                }
            }
            function narrowTypeByInstanceof(type, expr, assumeTrue) {
                var left = getReferenceCandidate(expr.left);
                if (!isMatchingReference(reference, left)) {
                    if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) {
                        return getTypeWithFacts(type, 2097152 /* TypeFacts.NEUndefinedOrNull */);
                    }
                    return type;
                }
                // Check that right operand is a function type with a prototype property
                var rightType = getTypeOfExpression(expr.right);
                if (!isTypeDerivedFrom(rightType, globalFunctionType)) {
                    return type;
                }
                var targetType;
                var prototypeProperty = getPropertyOfType(rightType, "prototype");
                if (prototypeProperty) {
                    // Target type is type of the prototype property
                    var prototypePropertyType = getTypeOfSymbol(prototypeProperty);
                    if (!isTypeAny(prototypePropertyType)) {
                        targetType = prototypePropertyType;
                    }
                }
                // Don't narrow from 'any' if the target type is exactly 'Object' or 'Function'
                if (isTypeAny(type) && (targetType === globalObjectType || targetType === globalFunctionType)) {
                    return type;
                }
                if (!targetType) {
                    var constructSignatures = getSignaturesOfType(rightType, 1 /* SignatureKind.Construct */);
                    targetType = constructSignatures.length ?
                        getUnionType(ts.map(constructSignatures, function (signature) { return getReturnTypeOfSignature(getErasedSignature(signature)); })) :
                        emptyObjectType;
                }
                // We can't narrow a union based off instanceof without negated types see #31576 for more info
                if (!assumeTrue && rightType.flags & 1048576 /* TypeFlags.Union */) {
                    var nonConstructorTypeInUnion = ts.find(rightType.types, function (t) { return !isConstructorType(t); });
                    if (!nonConstructorTypeInUnion)
                        return type;
                }
                return getNarrowedType(type, targetType, assumeTrue, isTypeDerivedFrom);
            }
            function getNarrowedType(type, candidate, assumeTrue, isRelated) {
                if (!assumeTrue) {
                    return filterType(type, function (t) { return !isRelated(t, candidate); });