Function narrowTypeByDiscriminantProperty

test/fixtures/snapshot/typescript.js:70817–70830

(type, access, operator, value, assumeTrue)

                });
            }
            function narrowTypeByDiscriminantProperty(type, access, operator, value, assumeTrue) {
                if ((operator === 36 /* SyntaxKind.EqualsEqualsEqualsToken */ || operator === 37 /* SyntaxKind.ExclamationEqualsEqualsToken */) && type.flags & 1048576 /* TypeFlags.Union */) {
                    var keyPropertyName = getKeyPropertyName(type);
                    if (keyPropertyName && keyPropertyName === getAccessedPropertyName(access)) {
                        var candidate = getConstituentTypeForKeyType(type, getTypeOfExpression(value));
                        if (candidate) {
                            return operator === (assumeTrue ? 36 /* SyntaxKind.EqualsEqualsEqualsToken */ : 37 /* SyntaxKind.ExclamationEqualsEqualsToken */) ? candidate :
                                isUnitType(getTypeOfPropertyOfType(candidate, keyPropertyName) || unknownType) ? removeType(type, candidate) :
                                    type;
                        }
                    }
                }
                return narrowTypeByDiscriminant(type, access, function (t) { return narrowTypeByEquality(t, operator, value, assumeTrue); });
            }
            function narrowTypeBySwitchOnDiscriminantProperty(type, access, switchStatement, clauseStart, clauseEnd) {
                if (clauseStart < clauseEnd && type.flags & 1048576 /* TypeFlags.Union */ && getKeyPropertyName(type) === getAccessedPropertyName(access)) {
                    var clauseTypes = getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd);