Auto-controlled props emit spurious warning when set to undefined (missing undefined check).

[DylanLukes]

Steps

For any auto-controlled property x, set both x and defaultX to undefined. For example, open and value in Dropdown.

Expected Result

These values should be treated as if they are undefined/do not exist.

Actual Result

Warning: Dropdown prop "open" is auto controlled. Specify either defaultOpen or open, but not both.

Version

0.68.0

Testcase

http://codepen.io/anon/pen/xdGPxz?editors=1111

Suggested Fix

Here in AutoControlledComponent.js, replace:

  if (defaultPropName in this.props && prop in this.props) { ... }

by

  if (_.has(this.props, defaultPropName) 
      && !_.isUndefined(this.props[defaultPropName])  
      && _.has(this.props, prop) 
      && !_.isUndefined(this.props[props]) {
    ...
  }

[DylanLukes]

In case anyone is wondering, "why on earth would you set open and defaultOpen to undefined?"...

The answer is interop with other languages targeting JS. For example, using ScalaJS with a Props facade type. When constructing an instance of Props, all of the factory/constructor arguments must be specified or defaulted to js.undefined, as there is no concept of an "unset" attribute.

[levithomason]

At first glance, I think this will still pass tests and be backward compatible. In fact, we likely should've been treating undefined as not present to begin with.

Let's get a PR and see what happens. Note, the logic can be reduced to this as we only care that they are undefined, not that they are present at all:

if (!_.isUndefined(this.props[defaultPropName]) && !_.isUndefined(this.props[prop]) {
  ...
}

[jonmajorc]

Hey @levithomason and @DylanLukes I am looking to contribute. I am guessing this issue is still open and is needing to be done, so I would love to help! This is also my first open source contribution too.