fix value check in renderClear

[hanwencheng]

I assume that it is common case that some one use options array with value started from 0:

Then we need to render clear button when the 0 value is chosen.
e.g.

[
  {value:0,label:'Aachen [Aix-la-Chapelle]',state:'NW'},
  {value:1,label:'Aalen',state:'BW'},
]

[JedWatson]

Thanks @hanwencheng!

[JedWatson]

I just realised you've applied this change to lib, I've patched it in src as well

[hanwencheng]

Thanks, @JedWatson I just find that the lib file has not been changed.

[kevinzwhuang]

@JedWatson @hanwencheng

Just looking back at this PR, it doesn't seem to have changed anything nor is it necessary. The behavior without this works normally event with a value of 0.

Let's take a look at what actually changed (this exists in master) -

-		!this.props.value
+		(!this.props.value || this.props.value === 0)

Source from master: https://github.com/JedWatson/react-select/blob/master/src/Select.js#L892

means that we're checking the whole object ( this.props.value ) to see if it is 0, such that the original example is checked like so:
{value:0,label:'Aachen [Aix-la-Chapelle]',state:'NW'} === 0

This does not make sense - since the real value to check is on this.props.value[this.props.valueKey] - but we don't even need to do that, since !this.props.value should pass just fine since the object exists.

The this.props.value === 0 check does not achieve its original goal - in fact, this check already worked previously on its own. !this.props.value should never evaluate to false if such an object existed.

The original check for !this.props.value was sufficient on its own.

[hanwencheng]

@kevinzwhuang Hi, the source code in master does not apply the origin commit

[TrevorBurnham]

PR to actually fix this: #1395