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    Connect a Vue.js Component to a server


    In this lesson we connect a Vue application to our Socket Server.

    We use the pulse from the previous lesson to display a graph using the Vuetify framework and then demonstrate 2 clients showing the graph changing in sync.



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    Instructor: For this lesson, we need a basic Vue application, which you can either create using the Vue CLI or using the Vue UI. In addition, we're going to install two additional dependencies. We're going to use the Vuetify material design component framework, and we're also going to make a reference to Vue Socket.IO package. Links to these will be in the description below.

    I've opened my Vue project, and if I just go into the package.json to confirm I have installed Vue Socket.IO and Vuetify's dependencies. Now, if I go into my source main, I'm going to make a reference to the Vuetify package and also a reference to the Vue Socket.IO package.

    We're going to tell Vue to use Vuetify and also tell Vue to use the Vue Socket.IO package. The syntax for the Socket.IO package needs to pass in the connection for the Socket.IO server and whether you want to be debugging.

    We're going to set debug true, and this will output more information to the browser console. The connection will be to our Express server, which we defined and set up in the previous lesson. It was running on localhost, port 8500.

    That's it for the main.js file. We won't be touching this file again. Let's now open the app.vue file, which has been generated for us by the Vue CLI. I'm just going to close the sidebar. We're going to get rid of all this and put our own markup in.

    Initially, I've created a template using the Vuetify framework. If I start the Vue application now, I'll quickly show what that looks like.

    As you can see, it's a very basic application layout that we're going to use. We're going to be putting components within this central section of this layout. This is an example of the Vue component we're going to build.

    Our Socket.IO server is emitting a random number, and we are going to use the Vuetify sparkline component to graph it in real time. Let's see how we build it. To start with, we're going to create a components folder within our source directory.

    Within that folder, we'll create a new file called graph.vue. This will be our graph component. To start with, I've got some markup I'm just going to paste in. This will be the Vuetify layout and components. This represents a card, and inside the card, we've got some information displayed, the heart rate.

    Then we've got the sparkline component itself. At the moment, this isn't hooked up to any sort of data or socket. Now, we can start with the script itself. We'll build our script log. We're going to start by holding inside our data block an array of heartbeats.

    This is what we're going to use to bind the graph. Coming back up to the sparkline, and we can use the value property to bind to heartbeats. Now, I want my graph to have an initial array of 10 heartbeats, which we're going to display.

    This will be before we receive any data from the server. To do that, we will set up a couple of methods. This method, randomHeartbeat, just generates a random number, similar to what the server did before. This method, takeInitialPulse, will populate our array with 10 random numbers.

    We need to call the takeInitialPulse when our Vue component is first created. We'll hook into the created life cycle. We'll have a quick look and see what this component looks like in its current state.

    Here, we can see the component being populated with the initial 10 random values. If I refresh the page, we get 10 different values. We now want to get the data from our Socket.IO server into our component.

    We do that by first creating a block called sockets. Then we have a label which matches the custom event name. In our case, that's going to be pulse. We have a function, and in that function then we have the value that's within the socket itself, that's being sent.

    We can take that value, and all we need to do then is push it into our heartbeats array. Heartbeats is reactive because it's within our data block, which means Vue will automatically update the graph with the new value.

    We also want to make sure that our array only has 10 values. We use the array.shift method. Let's bring up our browser and see that work running. Here, we have our Node server, and you can see we've got our custom event being fired, called pulse.

    If I start the server up, heartbeats gets sent. If I bring up my browser, which has my Vue component in there, we can see that the graph has been updated. The last step is to actually display the heart rate, so we'll do that now.

    We're going to add a new computed method, which is going to display the heartbeat. Then within the sparkline component, we can display it using the key property. Let's now retest our component and see what it looks like.

    I've restarted my server, refreshed the Vue component page, and as you can see, we can now see the heartbeat being displayed. If I bring across another connected client, we can see that both graphs are now synchronized with their values.

    In summary, the Socket server will start. It will emit a custom pulse event with a value of 110, in this case. The Vue single-file component will have a sockets block along with a pulse function. It will take the 110 value and push it to the heartbeats array, which is contained within the data block.

    The data block is reactive, and the sparkline component is bound that heartbeats array. This means the graph will be automatically updated as the value from the Socket server is sent. Because it's a Socket server, all connected clients will receive the data at the same time.