renderTransitionableChildren: function(sourceChildren) {
var children = {};
var childMapping = ReactTransitionKeySet.getChildMapping(sourceChildren);
var currentKeys = ReactTransitionKeySet.mergeKeySets(
this._transitionGroupCurrentKeys,
ReactTransitionKeySet.getKeySet(sourceChildren)
);
for (var key in currentKeys) {
// Here is how we keep the nodes in the DOM. ReactTransitionableChild
// knows how to hold onto its child if it changes to undefined. Here, we
// may look up an old key in the new children, and it may switch to
// undefined. React's reconciler will keep the ReactTransitionableChild
// instance alive such that we can animate it.
if (childMapping[key] || this.props.transitionLeave) {
children[key] = ReactTransitionableChild({
name: this.props.transitionName,
enter: this.props.transitionEnter,
onDoneLeaving: this._handleDoneLeaving.bind(this, key)
}, childMapping[key]);
}
}
this._transitionGroupCurrentKeys = currentKeys;
return children;
},
renderTransitionableChildren: function(sourceChildren) {
var children = {};
var childMapping = ReactTransitionKeySet.getChildMapping(sourceChildren);
var prevKeys = this._transitionGroupCurrentKeys;
var currentKeys = ReactTransitionKeySet.mergeKeySets(
prevKeys,
ReactTransitionKeySet.getKeySet(sourceChildren)
);
for (var key in currentKeys) {
// Here is how we keep the nodes in the DOM. ReactTransitionableChild
// knows how to hold onto its child if it changes to undefined. Here, we
// may look up an old key in the new children, and it may switch to
// undefined. React's reconciler will keep the ReactTransitionableChild
// instance alive such that we can animate it.
if (childMapping[key] || (this.props.transitionLeave && prevKeys[key])) {
children[key] = ReactTransitionableChild({
name: this.props.transitionName,
enter: this.props.transitionEnter,
onDoneLeaving: this._handleDoneLeaving.bind(this, key)
}, childMapping[key]);
} else {
// If there's no leave transition and the child has been removed from
// the source children list, we want to remove it immediately from the
// _transitionGroupCurrentKeys cache because _handleDoneLeaving won't
// be called. In normal cases, this prevents a small memory leak; in
// the case of switching transitionLeave from false to true, it
// prevents a confusing bug where ReactTransitionableChild.render()
// returns nothing, throwing an error.
delete currentKeys[key];
}
}
this._transitionGroupCurrentKeys = currentKeys;
return children;
},