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    Add Local State to a Functional Stateless Component using Recompose

    Tim KindbergTim Kindberg

    Learn how to use the 'withState' and 'withHandlers' higher order components to easily add local state to—and create a reusable local state pattern for—your functional stateless components. No need for classes!

    reactReact
    ^16.0.0
    recomposeRecompose
    Code

    Code

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    Transcript

    Transcript

    00:00 I want to be able to click the status and show and hide this list of other statuses. I also want to be able to hover over the name and show this tooltip, and I'd like it to go away when I mouseOut. We can use withState() and withHandlers() from recompose to accomplish this. First, let's work on the status.

    00:27 I'm going to add a withState() higher-order component here. It takes three properties -- the name of the state object that's going to hold the actual state value, then give it the name of the method that you'll be able to call to change the list shown variable, and the third parameter is your initial state. We'll set that to false. We need to wrap the functional stateless component.

    00:57 Now, our functional stateless component will receive list shown and setListVisible in addition to its normal props. We'd like to only show the status list if list shown is true. When we click on the span, we want to setListVisible to the opposite of whatever it was before.

    01:24 You can either call it directly with a value, like true or false, or you can call it with a function. In this case, you get the previous value. We can set it from x to not x. That will act as a toggle. When I save and refresh, it goes away, but now I'm able to click to show and hide it.

    01:48 I've added local state to this functional stateless component without using a React.createClass() or extends class method.

    01:54 Now let's do the tooltip. We're going to do the same thing. We'll call this state variable tooltip shown, and we'll call this method setTooltipVisible. We'll start this one with false also. Now we only want to show the tooltip if tooltip shown is true.

    02:18 We have to make sure we're importing it, so we're going to get tooltip shown and setTooltipVisible in as props because of the withState() higher-order component. Next onMouseEnter, we want to set the tooltipVisible to true. Here we're using just a raw value instead of a function. OnMouseLeave, we want to set the tooltipVisible to false.

    02:56 When I save and refresh, now I can hover over and leave the name to see a tooltip. I can click this to show the status. This is pretty good, but one cool thing about higher-order components is creating your own higher-order components that you can reuse across different scenarios. These two scenarios are similar. We're showing and hiding something.

    03:24 Let's create a withToggle() higher-order component. WithToggle() is going to have to compose a couple of different things. We'll set up withState() with the variable of toggledOn as our true/false variable. We'll have a method called toggle. We'll start it as false.

    03:51 Next we want to use withHandlers(). WithHandlers() takes an object where every key is the name of the handler that you'd like to pass into your component. We'll add a handler called show. Then the function takes in the props. We want to pull the toggle method off of that.

    04:14 You need to return another function, and this is going to be your actual handler function. This is the function that would receive the event object. I'll type e because I'm not going to be using it. Then here we get to call the toggle method. We want to set it to true because we're going to show. Next we'll do the same thing for hide. We will toggle it false.

    04:39 Last, we will make one called toggle as a convenience. It will override the toggle defined here. We'll call toggle, but this time we'll use the function signature. We'll get the current value, and we'll flip it. Now we have a general purpose with toggle higher-order component.

    05:03 Let's go replace what we've got down here. We can replace this as well. These now will take in toggledOn as the variable holding the state. This one will take in the toggle function, while this one will take in the show and hide functions.

    05:38 We can replace the entirety of this function with just a reference to toggle, and we have to change this to toggledOn. When it's toggledOn, show status list. Every time we click it, call toggle. Because we're using mouseEnter and mouseLeave down here, we'll replace this with show onMouseEnter and hide onMouseLeave.

    06:02 This needs to change to toggledOn. When toggledOn, show the tooltip. Show it on enter and hide it on leave. Should be able to refresh the page and see the exact same behavior.

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    Discuss