How to return value from function which is called multiple times by itself?

Question

There is some nested object data and I have to go through this several level deep until I find my result. So I use the findByKey function, which is calling itself as often as it is needed. Then it should return object.source , but I get undefined instead.

async function getData(lib, level) {
  // First get data from file
  const depsBuffer = await readFile(resolve('file.json'))
  const deps = JSON.parse(depsBuffer.toString('utf-8'))

  // Process data
  const result = findByKey(deps.dependencies, deps.dependencies)
  console.log(result) // returns undefined :-(
}

function findByKey(data, deps) {
  if (data.hasOwnProperty('target') && data.target === 'param') {
    return data
  }
  for (let i = 0; i < Object.keys(data).length; i++) {
    const element = data[Object.keys(data)[i]]
    if (typeof element === 'object') {
      let obj = findByKey(element, deps)
      if (obj != null) {
        if (RegExp(/.*/).test(obj.source)) return obj.source // <- Return this to `getData`
        // else if (!obj?.source?.startsWith('npm:')) findByKey(deps, deps)
      }
    }       
  }
}

Answer 1

I belive your issue is that

else if (!obj?.source?.startsWith('npm:')) findByKey(deps, deps)

should be

else if (!obj?.source?.startsWith('npm:')) return findByKey(deps, deps)

You are running it recursively, but you are not propagating the return value upward.