How to check for availability for a nested variable without checking all the preceding variable availability, in ReactNative?

Question

For example, in iOS Swift, I can do something like this:

if (self.user?.company?.pic?.phoneNumber != null) { doSomething() }

Without the need t

Answer 1

If you can’t use optional chaining which is still a proposal but available via babel plugin you could use a recursive utility function to test for the presence of each path segment:

const pluck = (item, path) => {
  const [, part, rest] = /^([^.]+)\.*(.*)/.exec(path) || [];
  if (!part) {
    return null;
  }
  const o = (item || {})[part];
  if (o == null) {
    return null;
  }

  return rest.length ? pluck(o, rest) : o;
};

if (pluck(this.state, ‘user.company.pic.phoneNumber’)) {
  doSomething();
}