lib/rules/file-extension-in-import.js
function getExistingExtensions(filePath) {
    const basename = path.basename(filePath, path.extname(filePath))
    try {
        return fs
            .readdirSync(path.dirname(filePath))
            .filter(
                filename =>
                    path.basename(filename, path.extname(filename)) === basename
            )
            .map(filename => path.extname(filename))
    } catch (_error) {
        return []
    }
}
function getExistingExtensions(filePath) {
    const basename = path.basename(filePath, path.extname(filePath))
    try {
        return fs
            .readdirSync(path.dirname(filePath))
            .filter(
                filename =>
                    path.basename(filename, path.extname(filename)) === basename
            )
            .map(filename => path.extname(filename))
    } catch (_error) {
        return []
    }
}
Get all file extensions of the files which have the same basename.
@param {string} filePath The path to the original file to check.
@returns {string[]} File extensions.