JavaScript realtime chart quick start

After following this guide you will have a chart in a webpage that you can publish new data-points to from your server. If you have any questions get in touch.

Get your free API keys

Create an account , then create a Channels app. Go to the “Keys” page for that app, and make a note of your app_id, key, secret and cluster.

Create your webpage

We’ll make the chart UI using Google Charts (but you can use any common charting library). Copy-paste the following code into index.html. Replace 'APP_KEY' and 'APP_CLUSTER' with the values from your dashboard. Then open index.html in your browser:

<html>
  <body>
    <div id="chart_div" style="width: 100%; height: 500px;"></div>
    <script src="https://www.gstatic.com/charts/loader.js"></script>
    <script src="https://js.pusher.com/7.2.0/pusher.min.js"></script>
    <script>
      google.charts.load("current", { packages: ["corechart"] });
      google.charts.setOnLoadCallback(() => {
        // Instead of hard-coding the initial table data,
        // you could fetch it from your server.
        const dataTable = google.visualization.arrayToDataTable([
          ["Year", "Price"],
          [2013, 400],
          [2014, 460],
        ]);
        const chart = new google.visualization.AreaChart(
          document.getElementById("chart_div")
        );
        const options = {
          title: "1 BTC in USD",
          hAxis: { title: "Year", titleTextStyle: { color: "#333" } },
          vAxis: { minValue: 0 },
          animation: { duration: 100, easing: "out" },
        };
        chart.draw(dataTable, options);
        let year = 2015;
        Pusher.logToConsole = true;
        const pusher = new Pusher(
          "APP_KEY", // Replace with 'key' from dashboard
          {
            cluster: "APP_CLUSTER", // Replace with 'cluster' from dashboard
            forceTLS: true,
          }
        );
        const channel = pusher.subscribe("price-btcusd");
        channel.bind("new-price", (data) => {
          const row = [year++, data.value];
          dataTable.addRow(row);
          chart.draw(dataTable, options);
        });
      });
    </script>
  </body>
</html>

This page is now waiting for new-price events on the price-btcusd channel. When an event comes in, it will extract the value field and add this as a new data point on the right of the chart!

Trigger events from your server

Your server should trigger events called new-price on a channel called price-btcusd. Each example below uses one of the official Pusher Channels server SDKs to trigger the events.

// First, run 'npm install pusher'
const Pusher = require("pusher");
const pusher = new Pusher({
  appId: "APP_ID", // Replace with 'app_id' from dashboard
  key: "APP_KEY", // Replace with 'key' from dashboard
  secret: "APP_SECRET", // Replace with 'secret' from dashboard
  cluster: "APP_CLUSTER", // Replace with 'cluster' from dashboard
  useTLS: true,
});
// Trigger a new random event every second. In your application,
// you should trigger the event based on real-world changes!
setInterval(() => {
  pusher.trigger("price-btcusd", "new-price", {
    value: Math.random() * 5000,
  });
}, 1000);

<?php
// First, run 'composer require pusher/pusher-php-server'
require __DIR__ . '/vendor/autoload.php';

$pusher = new Pusher\Pusher(
  "APP_KEY", // Replace with 'key' from dashboard
  "APP_SECRET", // Replace with 'secret' from dashboard
  "APP_ID", // Replace with 'app_id' from dashboard
  array(
    'cluster' => 'APP_CLUSTER' // Replace with 'cluster' from dashboard
  )
);
// Trigger a new random event every second. In your application,
// you should trigger the event based on real-world changes!
while (true) {
  $pusher->trigger('price-btcusd', 'new-price', array(
    'value' => rand(0, 5000)
  ));
  sleep(1);
}

# First, run 'pip install pusher'
import pusher
import random
import time pusher_client = pusher.Pusher(
  app_id='APP_ID', # Replace with 'app_id' from dashboard
  key='APP_KEY', # Replace with 'key' from dashboard
  secret='APP_SECRET', # Replace with 'secret' from dashboard
  cluster='APP_CLUSTER', # Replace with 'cluster' from dashboard
  ssl=True
)
# Trigger a new random event every second.In your application,
# you should trigger the event based on real-world changes!
while True:
  pusher_client.trigger('price-btcusd', 'new-price', {
    'value': random.randint(0, 5000)
  })
  time.sleep(1)

If there isn’t an example in your language, have a look on our server SDKs page, or get in touch.

Finally, go back to your browser to see the realtime data appearing in the chart!

Where next?

If you had any trouble, get in touch.
For the core concepts, read Understanding Pusher Channels.
For the features this quick start uses, see connections , publish/subscribe over channels , and the JavaScript client library.