in infra/is-ngcc-necessary.ts [43:57]
function guessTypingsFromPackageJson(packagePath: string, packageJson: any) {
const SUPPORTED_FORMAT_PROPERTIES = ['fesm2015', 'fesm5', 'es2015', 'esm2015', 'esm5', 'main', 'module', 'browser'];
for (const prop of SUPPORTED_FORMAT_PROPERTIES) {
const field = packageJson[prop];
if (typeof field !== 'string') {
continue;
}
const relativeTypingsPath = field.replace(/\.js$/, '.d.ts');
const typingsPath = resolve(packagePath, relativeTypingsPath);
if (existsSync(typingsPath)) {
return typingsPath;
}
}
return null;
}