@jsdocs-io/extractor/src/api-extractor/type-checker.ts

import * as tsm from 'ts-morph';
import { log } from '../utils/log';

export type TypeChecker = ({
    declaration,
}: {
    declaration: tsm.Node;
}) => string;

export function getTypeChecker({
    project,
}: {
    project: tsm.Project;
}): TypeChecker {
    const projectTypeChecker = project.getTypeChecker();

    return ({ declaration }) => {
        let type = 'any';

        try {
            const typeChecker = projectTypeChecker.compilerObject;
            const { compilerNode } = declaration;
            const nodeType = typeChecker.getTypeAtLocation(compilerNode);
            type = typeChecker.typeToString(
                nodeType,
                compilerNode,
                tsm.ts.TypeFormatFlags.NoTruncation |
                    tsm.TypeFormatFlags.UseAliasDefinedOutsideCurrentScope
            );
        } catch (err) {
            // istanbul ignore next
            log('type checker: error: %O', { err });
        }

        return type;
    };
}