score:1
there's no this
with a functional component. to access the props you can change it to this:
const todoapp = (props) => {
console.log(props)
return (
<div>
some text1
</div>
)
}
score:1
mapstatetoprops
maps the some parts of your redux state to props of your react component.
state comes from your store
. in fact, you can take a look at your current state at any point by calling store.getstate()
. when you do createstore(todos)
, this creates the state based on the todos
reducer. as you can see in your todos
reducer, your initial state comes from stateobject
, which is defined up top.
so, back to mapstatetoprops
. all you need to do in that functions is to return the object, where keys will be the props and values will be the values obtained from the redux state. here's an example of mapstatetoprops
:
const mapstatetoprops = function (state) {
return {
propname: state
}
}
now when you do the console.log(this.props)
inside render(), you can see the whole state being stored inside this.props.propname
. that is achieved by mapstatetoprops
.
a little bit of theory on this: each time an action is dispatched, every mapstatetoprops
you have in your app is called, props are applied to every component you created, and if any props have changed, that component will re-render. this kind of behaviour is provided for you via connect
function. so you don't have to implement this behaviour for every component: all you need to do is to apply it like so: const connectedcomponent = connect(mapstatetoprops)(somecomponent)
and use connectedcomponent
instead of somecomponent
.
Source: stackoverflow.com
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