In the case of having an animated node which is, after the leave-transition has been activated, then re-added in a render call causes React to 'break'. This is especially noticeable if you spam to removal and re-addition of an item in a ReactTransitionGroup.
This fix simply stops the leave transition and restarts the enter transition.
It is valuable to know when the number of children in a TransitionGroup is going
to increase or decrease, since we might want to apply extra animations.
For instance, when used with overflow:auto, we might want to apply different css
based on it overflowing or not - to do this we need to calculate this after new
nodes has entered and after nodes has been removed.
Context is adding another argument that shifts all of them by one. Since we can already use this.getDOMNode(), it doesn't really make sense to pass it as an argument to that function.
Summary:
adds `this.context` which you can think of as implicit props, which are passed automatically down the //ownership// hierarchy.
Contexts should be used sparingly, since they essentially allow components to communicate with descendants (in the ownership sense, not parenthood sense), which is not usually a good idea. You probably would only use contexts in places where you'd normally use a global, but contexts allow you to override them for certain view subtrees which you can't do with globals.
The context starts out `null`:
var RootComponent = React.createClass({
render: function() {
// this.context === null
}
});
You should **never** mutate the context directly, just like props and state.
You can change the context of your children (the ones you own, not `this.props.children` or via other props) using the new `withContext` method on `React`:
var RootComponent = React.createClass({
render: function() {
// this.context === null
var children = React.withContext({foo: 'a', bar: 'b'}, () => (
// In ChildComponent#render, this.context === {foo: 'a', bar: 'b'}
<ChildComponent />
));
// this.context === null
}
});
Contexts are merged, so a component can override its owner's context **for its children**:
var ChildComponent = React.createClass({
render: function() {
// this.context === {foo: 'a', bar: 'b'} (for the caller above)
var children = React.withContext({foo: 'c'},() => (
// In GrandchildComponent#render,
// this.context === {foo: 'c', bar: 'b'}
<GrandchildComponent />
));
// this.context === {foo: 'a', bar: 'b'}
}
});
This introduces `ReactLink` which is a super lightweight way to do two-way binding for React.
If you want to use a controlled form input today, it's a lot of lines of code:
http://jsfiddle.net/T3z3v/
Look how many times `name` is repeated in there. And you have to remember to wire up event handles and pass the right state and
right event handler for *each* form field. It's really annoying.
With ReactLink, you can "link" a form value to a state field. It's just some simple sugar around the value prop/onChange
convention:
https://gist.github.com/petehunt/6689857
Ah, much nicer! And requires very little core changes or extra bytes. `ReactLink` just wraps the current value and "request
change" handler into a little object and provides some sugar to create some from composite component state.
This introduces <ReactTransitionGroup>, a component that works a lot
like Angular's ng-animate.
The problem we're currently facing is twofold:
1. We don't really have a great convention surrounding CSS transitions
in React
2. (harder) we can't animate nodes that are leaving the DOM, as their
nodes are instantly destroyed.
To solve the first issue I've adopted Angular's convention. It's
implemented in ReactTransitionableChild.
The second part is what's tricky. To do this I've implemented three modules:
- ReactTransitionableChild, which can keep its old children around if they
change to null
- ReactTransitionKeySet, which can look at a prev and next set of child
keys and merge them in a reasonable way
- ReactTransitionGroup, which combines ReactTransitionableChild and
ReactTransitionKeySet to keep nodes that are leaving the DOM in the
DOM until their animations are complete
Ben Alpert
Pete Hunt
Nicholas Bergson-Shilcock
Cartas
Sean Kinsey
Christopher Chedeau
Marshall Roch
Simon Højberg
Ian Obermiller
Paul O'Shannessy