Where do I place side effects in a React app? - javascript

I am building a React app and wanted to determine the cleanest way to achieve the following behavior.
I have a List component that renders N Details components. Each Details component has a Connect button component that will trigger some behavior. There are 3 different behaviors:
immediately make API call, which requires no state change
open a modal and make an API call based on values in the input modal, which involves changing app State to render a modal, and then making an API call when they confirm the modal
open a pop-up window and make an API call based on returned values from that pop-up window.
To achieve this, I can pass down 3 separate callbacks to the Connect button component, and switch based on the value of the Detail component so it knows which callback to pass. However, this means the Detail component has some "switch-on-type" behavior. For example,
if (this.props.name === `immediate-connection`) {
callbackToPass = this.props.callApi;
} else if (this.props.name === `trigger-modal`) {
callbackToPass = this.props.changeStateToRenderModal;
}... // etc.
I could also build 3 separate components that encapsulate the behavior and have them render from Details but this doesn't avoid the switch-on-type behavior.
Another way to phrase this question is how to get identical behavior from the Connect buttons when their implementation is different? Do I encapsulate this behavior in a sub-component rendered by the Connect button or do I lift it it up to when State would be changed?

Related

Trigger state change of a React component from Chrome extension on a Facebook post

I'm doing a Chrome plugin for Facebook and I want to modify a post using external javascript. I can change the textContent of a span but the state is not changed and the Save button is not activated.
The html looks like that :
<div class="" data-block="true" data-editor="1477r" data-offset-key="a699d-0-0">
<div data-offset-key="a699d-0-0" class="_1mf _1mj">
<span data-offset-key="a699d-0-0">
<span data-text="true">test</span>
</span>
</div>
</div>
The component in React Developper Tools :
[
I profiled a change of the text and this is the result for a 6 ms timeline activating the save button.
There are ways to modify a React input but did not found ways for my problem :
https://github.com/facebook/react/issues/11488
https://github.com/facebook/react/issues/10135#issuecomment-314441175
How can you change a Facebook post and his state with external javascript?
What would you do?
That’s not possible, you can’t imperatively mutate a React element tree from outside the app. You’d have to declaratively render a tree, either by modifying Facebook’s frontend code (beware of legal ramifications) or implementing your own post UI.
While it's nearly impossible to change the state of React component from your plugin, nothing stops you from emulating user's input by sending keystrokes, mouse clicks etc. The only thing you need it to figure out - which DOM-element listens to these events (not necessary one of those 4 in you question).
About the possibility of direct state change: let's say the component you need to changes is a functional one. Then it has a form of
Component() {
const [state, setState] = useState(...)
...
setState(something)
...
}
so you need to somehow access the setState function of the component. But how? It's private to the function call. If you think that instead you can call the useState directly, then be aware that in another component it will return another setState. I have no idea what would happen if you'll call useState outside of a component, but surely it will not be able to guess which setState you want.
If you want you can check the source code of react-devtools to find out how you can dig out the state from the depths of React... but would you really want to try? And for what? The next time Facebook or React will be updated your code will definitely break.

Parent component triggering action in multiple child components - preferred way in React (hooks)

I have a parent component which has three other components, A B and C.
Each of these components has its own set of fields that can be saved. These are different object types. And now, when user clicks "Save", I want to trigger a save action in each of these components. Each of them has its own error handling, messaging etc.
How to handle it? At the moment I'm just using references, but according to this post (Call child method from parent) this is not encouraged. How to implement it in "React" way of thinking?

Can my React component listen to changes in the server and update itself?

I have a React component that renders a list of items. I have a different component which allows user to add a new item. This new item is created by making an async call to the server. Can the component that renders the list listen to changes in the server and update itself.
The new item is added through a modal hence when the modal is closed, an action needs to be triggered to update the component that renders the list of items. Right now I am having to refresh the browser to reflect the changes in the UI.
If I close my modal, there is no way I am triggering a change to the component that renders the list of items. I thought about adding the result of the async call which is a list item to the state using redux as a way to cause a re-render. However, the client I am interfacing with does not give back all the properties that the items requires (as a part of the Typescript interface). Hence this method won't work. An alternate way to force a re-render to the component that displays the list. But again, can't really think of a way that would be work and how would I trigger the componentDidUpdate hook.
if (the server supports webSockets) {
use webSockets;
} else {
use socket.io;
}

Using react router without loosing "setState" state?

I have a React app that takes the user through various steps. I want to have the ability to use the browser's "back" button to go back to a previous step. Now I'm thinking of using react-router to do this.
Currently, I am simply reacting to events and calling setState on my top-level component.
My question: Does all state have to be reflected in the URL, or saved into local storage? Or can I keep the component's state and just have react-router change some props on the top-level component? When I do that, do I risk loosing the component's state (e.g. because React doesn't identify the old and the new components)?
I want to have simple URLs like /step1, /step2... . These do not reflect everything that is going on in the app. Specifically, I don't need or want the ability to directly enter such an URL. There are also privacy concerns. I am happy with having the application's state in the main component's ephemeral state. In other words, my application's state is not a pure function of the route.
I want to mainly use react-router to make the back button act as a glorified undo / go to last step button, and only secondly to navigate to other components. Any idea or small snippet showing how to do that? Or is react-router not suited for this?
When React navigates from one component hierarchy to another (such as react-router links / history navigation) it only unmounts the components that do not exist in the new component hierarchy. State is only lost in unmounted components. If your state is properly stored at the top level which only goes through rerendering and not remounting, you should retain it.

Ngrx update reducer if component is on the page

I have two components on a page, an update user form and a history of events. They are represented by two reducers (user and events). I want to update the list of events in the store (by calling an API) once once the user has been updated. However, the events should only be updated if the events component is on the page.
What's the best way to achieve this? The only solution I like the idea of is to have a success handler in a parent of the form / event components which dispatches an action which is caught by an effect which will then refresh the list of events. I was hoping this is something I could achieve entirely with effects but I obviously don't know if the component Is on the page and I also need access to route params. Does anyone have any better solutions or can see an issue with this solution?
Typically, the fact that the Events component is shown on the screen represents some sort of part of the "business logic/process" which is likely already represented in the store state. If it is not the case, you seem to need to add it in some way and update it when your events component initializes (ngOnInit) and is destroyed (ngOnDestroy).
Once it is part of the store, you can use it as part of the effect.

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