Maps in Immutable have a [setIn method](https://facebook.github.io/immutable-js/docs/#/Map/setIn) that makes it easy to set deep values:

    peopleImmutable = peopleImmutable.setIn([&quot;Thomas&quot;, &quot;nickname&quot;], &quot;Mr. T&quot;);

Or, using `split` to generate the array:

    peopleImmutable = peopleImmutable.setIn(&quot;Thomas.nickname&quot;.split(&quot;.&quot;), &quot;Mr. T&quot;);

According to [docs][1] state of react app has to be something serializable.
What about classes then?

Let&#39;s say I have a ToDo app.
Each of `Todo` items has properties like `name`, `date` etc. so far so good.
Now I want to have methods on objects which are non serializable. I.e. `Todo.rename()` which would rename todo and do a lot of other stuff.

As far as I understand I can have function declared somewhere and do `rename(Todo)` or perhaps pass that function via props `this.props.rename(Todo)` to the component.

I have 2 problems with declaring `.rename()` somewhere: 
1) Where? In reducer? It would be hard to find all `would be instance` methods somewhere in the reducers around the app.
2) Passing this function around. Really? should I manually pass it from all the higher level components via &lt;Component rename={rename} /&gt;
And each time I have more methods add a ton of boilerplate to just pass it down?
Or always do &lt;Component {...this.props}&gt; and hope that I only ever have one rename method for one type of object. Not `Todo.rename()` `Task.rename()` and `Event.rename()`


That seems silly to me. Object should know what can be done to it and in which way. Is not it?

What I&#39;m missing here?





  [1]: http://rackt.github.io/redux/docs/Glossary.html#state

How to put methods onto the objects in Redux state?

I would like my app to run special code (e.g. resetting its state) when running in UI Testing mode. I looked at environment variables that are set when the app is running from UI Testing and there aren&#39;t any obvious parameters to differentiate between the app running normally vs in UI Testing. Is there a way to find out?

Two workarounds that I&#39;m not satisfied with are:

 1. Set `XCUIApplication.launchEnvironment` with some variable that I later check in the app. This isn&#39;t good because you have to set it in the `setUp` method of each test file. I tried setting the environment variable from the scheme settings but that doesn&#39;t propagate to the app itself when running UI Testing tests.
 2. Check for the lack of existence of the environment variable `__XPC_DYLD_LIBRARY_PATH`. This seems very hacky and might only be working now because of a coincidence in how we have our target build settings set up.

How to detect if iOS app is running in UI Testing mode

When working with plain JavaScript objects it&#39;s easy to change a deeply nested object property:

    people.Thomas.nickname = &quot;Mr. T&quot;;

But with Immutable I have to go through each property&#39;s ancestors before I have a new people object:

    var thomas = peopleImmutable.get(&quot;Thomas&quot;);
    var newThomas = thomas.set(&quot;nickname&quot;, &quot;Mr .T&quot;);
    peopleImmutable = peopleImmutable.set(&quot;Thomas&quot;, newThomas);

Is there a more elegant way to write this?

How can I set a deeply nested value in Immutable.js?

When working with plain JavaScript objects it's easy to change a deeply nested object property:
<pre><code class="hljs language-ini">people.Thomas.nickname = "Mr. T";
</code></pre>
But with Immutable I have to go through each property's ancestors before I have a new people object:
<pre><code class="hljs language-ini">var thomas = peopleImmutable.get("Thomas");
var newThomas = thomas.set("nickname", "Mr .T");
peopleImmutable = peopleImmutable.set("Thomas", newThomas);
</code></pre>
Is there a more elegant way to write this?

I&#39;m trying to find the proper way to define some components which could be used in a generic way:

    &lt;Parent&gt;
      &lt;Child value=&quot;1&quot;&gt;
      &lt;Child value=&quot;2&quot;&gt;
    &lt;/Parent&gt;

There is a logic going on for rendering between parent and children components of course, you can imagine `&lt;select&gt;` and `&lt;option&gt;` as an example of this logic.

This is a dummy implementation for the purpose of the question:

    var Parent = React.createClass({
      doSomething: function(value) {
      },
      render: function() {
        return (&lt;div&gt;{this.props.children}&lt;/div&gt;);
      }
    });

    var Child = React.createClass({
      onClick: function() {
        this.props.doSomething(this.props.value); // doSomething is undefined
      },
      render: function() {
        return (&lt;div onClick={this.onClick}&gt;&lt;/div&gt;);
      }
    });

The question is whenever you use `{this.props.children}` to define a wrapper component, how do you pass down some property to all its children?


How to pass props to {this.props.children}

I have a `Map` like this:

    const m = new Map();
    m.set(&#39;key1&#39;, {})
    .
    m.set(&#39;keyN&#39; {})

the `Map`can have 1 or many items. Can I get the first item by index, without `m.get(&#39;key1&#39;)` and without a iterator loop?

like: `m.get()[0]`


First item from a Map on JavaScript ES2015

I&#39;ve read [this answer][1], [reducing boilerplate][2], looked at few GitHub examples and even tried redux a little bit (todo apps). 

As I understand, [official redux doc motivations][3] provide pros comparing to traditional MVC architectures. BUT it doesn&#39;t provide an answer to the question: 

**Why you should use Redux over Facebook Flux?** 

*Is that only a question of programming styles: functional vs non-functional? Or the question is in abilities/dev-tools that follow from redux approach? Maybe scaling? Or testing?*

*Am I right if I say that redux is a flux for people who come from functional languages?* 

**To answer this question you may compare the complexity of implementation redux&#39;s motivation points on flux vs redux.**

Here are motivation points from [official redux doc motivations][3]:

 1. Handling optimistic updates (*as I understand, it hardly depends on 5th point. Is it hard to implement it in facebook flux?*)
 2. Rendering on the server (*facebook flux also can do this. Any benefits comparing to redux?*)
 3. Fetching data before performing route transitions (*Why it can&#39;t be achieved in facebook flux? What&#39;s the benefits?*)
 4. Hot reload (*It&#39;s possible with [React Hot Reload][4]. Why do we need redux?*)
 5. Undo/Redo functionality
 6. Any other points? Like persisting state...

  [1]: https://stackoverflow.com/questions/32021763/what-could-be-the-downsides-of-using-redux-instead-of-flux
  [2]: http://redux.js.org/docs/recipes/ReducingBoilerplate.html
  [3]: http://redux.js.org/docs/introduction/Motivation.html
  [4]: http://gaearon.github.io/react-hot-loader/

Why use Redux over Facebook Flux?

How can I timeout a promise after certain amount of time?
I know Q has a promise timeout, but I&#39;m using native NodeJS promises and they don&#39;t have .timeout function.

Am I missing one or its wrapped differently?

Alternatively, Is the below implementation good in means of not sucking up memory, actually working as expected?

Also can I make it somehow wrapped globally so I can use it for every promise I create, without having to repeat the setTimeout and clearTimeout code?

    function run() {
        logger.info(&#39;DoNothingController working on process id {0}...&#39;.format(process.pid));
    
        myPromise(4000)
            .then(function() {
                logger.info(&#39;Successful!&#39;);
            })
            .catch(function(error) {
                logger.error(&#39;Failed! &#39; + error);
            });
    }
    
    function myPromise(ms) {
        return new Promise(function(resolve, reject) {
            var hasValueReturned;
            var promiseTimeout = setTimeout(function() {
                if (!hasValueReturned) {
                    reject(&#39;Promise timed out after &#39; + ms + &#39; ms&#39;);
                }
            }, ms);
    
            // Do something, for example for testing purposes
            setTimeout(function() {
                resolve();
                clearTimeout(promiseTimeout);
            }, ms - 2000);
        });
    }

Thanks! 

NodeJS Timeout a Promise if failed to complete in time

I am currently working on [React JS][1] and [React Native][2] frameworks. On the half way road I came across Immutability or the [Immutable-JS library][3], when I was reading about Facebook&#39;s Flux and Redux implementation.

The question is, why is immutability so important? What is wrong in mutating objects? Doesn&#39;t it make things simple?

Giving an example, let us consider a simple **News reader** app with the opening screen being a list view of news headlines.

If I set say an **array of objects** with a value **initially** I can&#39;t manipulate it. That&#39;s what immutability principle says, right? (Correct me if I am wrong.)
But, what if I have a new News object that has to be updated? In usual case, I could have just added the object to the array.
How do I achieve in this case? Delete the store and recreate it?
Isn&#39;t adding an object to the array a less expensive operation?


  [1]: http://github.com/facebook/react
  [2]: https://github.com/facebook/react-native
  [3]: https://github.com/facebook/immutable-js

Why is immutability so important (or needed) in JavaScript?

I am missing a option how to get the index number inside the `map` function using `List` from `Immutable.js`:

```var list2 = list1.map(mapper =&gt; { a: mapper.a, b: mapper.index??? }).toList();
```

[Documentation shows][1] that `map()` returns `Iterable&lt;number, M&gt;`. Is there any elegant way to what I need?


  [1]: http://facebook.github.io/immutable-js/docs/#/List/map

Content Type	Original Author	Original Content on Stackoverflow
Question	Matt Zeunert	View Question on Stackoverflow
Solution 1 - Javascript	Matt Zeunert	View Answer on Stackoverflow

How can I set a deeply nested value in Immutable.js?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

How to detect if iOS app is running in UI Testing mode

How to put methods onto the objects in Redux state?

Attributions