google-charts-node

This package allows you to render Google Charts on the server as PNG images. It's part of QuickChart, which offers a suite of tools for rendering charts & graphs as images.

It is based on the Google Visualization API and is made possible through the use of puppeteer, which uses the Chromium browser for "headless" rendering.

For a more detailed walkthrough, see Server-side image rendering for Google Charts on QuickChart.

Installation

This project is available on NPM.

npm install google-charts-node

Example

const GoogleChartsNode = require('google-charts-node');

// Define your chart drawing function
function drawChart() {
  const data = google.visualization.arrayToDataTable([
    ['City', '2010 Population',],
    ['New York City, NY', 8175000],
    ['Los Angeles, CA', 3792000],
    ['Chicago, IL', 2695000],
    ['Houston, TX', 2099000],
    ['Philadelphia, PA', 1526000]
  ]);

  const options = {
    title: 'Population of Largest U.S. Cities',
    chartArea: {width: '50%'},
    hAxis: {
      title: 'Total Population',
      minValue: 0
    },
    vAxis: {
      title: 'City'
    }
  };

  const chart = new google.visualization.BarChart(container);
  chart.draw(data, options);
}

// Render the chart to image
const image = await GoogleChartsNode.render(drawChart, {
  width: 400,
  height: 300,
});

This produces the following image:

The only requirements of your drawChart function are that you must:

• Define a chart variable or return your chart.
• Use the provided container variable to render your chart.

Example with arguments

To use outside values in your drawChart function, call render with a Javascript string. Here's an example:

const myArg = 12345;
const myOtherArg = [5, 10, 15, 20];
const drawChartStr = `
  // Create the data table.
  var data = new google.visualization.DataTable();
  data.addColumn('string', 'Topping');
  data.addColumn('number', 'Slices');
  data.addRows([
    ['Mushrooms', ${myArg}],
    ['Onions', ${myOtherArg[0]}],
    ['Olives', ${myOtherArg[1]}],
    ['Zucchini', ${myOtherArg[2]}],
    ['Pepperoni', ${myOtherArg[3]}],
  ]);
  // Set chart options
  var options = { title: 'How Much Pizza I Ate Last Night' };
  // Instantiate and draw our chart, passing in some options.
  var chart = new google.visualization.PieChart(document.getElementById('chart_div'));
  chart.draw(data, options);
`;
const image = await GoogleChartsNode.render(drawChartStr, {
  width: 400,
  height: 300,
});

Usage

render(drawChartFunction, options) -> Buffer

The library exposes a single function, render.

drawChartFunction is a Function or Javascript string that is evaluated in order to draw the chart. You should put your regular drawChart Google Charts function here.

options is a dictionary containing some settings and parameters:

• width: Width of chart canvas (default 100%)
• height: Height of chart canvas (default 100%)
• packages: Array of Google Charts packages to import (default ['corechart'])
• mapsApiKey: Google Maps API key (used only for geochart and map charts)

More examples

See the examples/ directory for more examples of different charts.