How is 'outDir' in tsconfig.json resolved?

Question

Does baseUrl or current working directory affect it? And, more generally, where is this documented?

Answer 1

It does not seem to be documented anywhere, but it's resolved relative to the directory of tsconfig.json file, and it's not affected by baseUrl - baseUrl is for module resolution only.

The source, slightly reformatted:

    const result = parseJsonText(configFileName, configFileText);
    const cwd = host.getCurrentDirectory();
    return parseJsonSourceFileConfigFileContent(
        result, 
        host, 
        getNormalizedAbsolutePath(getDirectoryPath(configFileName), cwd),
        optionsToExtend, 
        getNormalizedAbsolutePath(configFileName, cwd)
    );

The third argument for parseJsonSourceFileConfigFileContent is the base for resolving relative paths in tsconfig.json, and as you see it comes from configFileName which is the name of tsconfig.json file.