We will add the functions in our script.js file. Let's create the helper JS functions for these two elements.
Adding a Few Helper Functionsĭrawing the bar chart only requires knowing how to draw two elements: To draw on the canvas, we only need a reference to its 2D context, which contains all the drawing methods. This gets a reference to the canvas element and then sets the width and height to 300px.
We then load the JS code via the tag.Īdd the following code in the script.js file: var m圜anvas = document.getElementById("m圜anvas") We have the element with the ID m圜anvas so that we can reference it in our JS code. We'll keep things very simple and add the following code in index.html: This will contain the JavaScript code for drawing the bar chart. Also inside the project folder, create a file and call it script.js.Inside the project folder, create a file and call it index.html. screenshot shown (Select data and click Insert > Insert Column or Bar Chart ): 2.Create a folder to hold the project files let's call this folder bar-chart-tutorial.To start drawing using JavaScript and the HTML5 canvas, we will need to set up our project like this:
Drawing the Bar Chart Using JavaScript Setting Up the JS Project Now that we know the components of a bar chart, let's see how we can write the JavaScript code to draw a chart like this. Chart legend (4): shows the correspondence between the colors used and the data they represent.The bars (3): color-filled rectangles with dimensions proportional to the data represented.Cannot be combined with: Doughnut, Pie, Bar, Stacked Bar charts. In column charts, axisX is the horizontal Axis and axisY is the vertical Axis. A column chart is useful to compare dataPoints in one or more dataSeries. The chart grid (2): gives a reference system so that the visual representation can be easily understood. Column charts are rectangular bars with lengths proportional to the values that they represent.The chart data: these are sets of numbers and associated categories which are represented by the chart.Let's take a look at the components that make up a bar chart, regardless of its type:
In an earlier tutorial, we covered how to draw a pie chart or doughnut chart using HTML5 canvas.