What is it?
This plugin provides accessibility enhancements for a very versatile chart library from amCharts.com. Once applied, the plugin enables navigation for keyboard users and provides the necessary support for screen reader users.
Watch a screencast of the plugin in action or try the live demo below:
For example, here is the plugin called after amStock.js:
After the plugin is applied to the amCharts code, the following keyboard navigation becomes possible:
- When focused on the chart, the left and right arrow keys navigate between the data points of the chart. To aid the navigation, the cursor tooltip is shown when the arrow keys are pressed.
- The Tab and Shift+Tab keys navigate between the chart, "Start Date" and "End Date" sliders that allow the user to control the date ranges for the chart.
Screen reader features
- When navigating between the data points on the chart, the values on the x-axis and y-axis will be spoken.
- A "start of chart" and "end of chart" messages will be spoken when the start and the end of chart data is reached.
- When changing the values for the "start date" or the "end date" sliders, the values will be read as well.
- This plugin utilizes WAI-ARIA roles, states and properties to enable the meaningful spoken feedback for screen reader users.
- The chart is a Div container with a role of application and aria-label and tabIndex of 0 in order to receive focus.
- A status Div is used to announce the tooltip to screen reader users. It is hidden offscreen and aria-live is set to polite and aria-atomic is set to true.
- The left slider is an SVG element which has aria-label, aria-valuemin, aria-valuemax, aria-valuetext and aria-valuenow.
- The right slider is also an SVG element with aria-label, aria-valuemin, aria-valuemax, aria-valuetext and aria-valuenow.
The slider functionality doesn't work in Firefox as there is a bug in this browser which prevents an SVG element inside an SVG document getting focused. See this issue for more information.
Recently updated to work with amstockchart_3.20.5 . The changes are in branch 3.20.5 .
Feedback and Contributions
Please do not hesitate to open an issue or send a pull request if something doesn't work or you have ideas for improvement. For instructions on how to contribute to this project please read the contribution guide.
The rest of the PayPal Accessibility Team
Copyright and license
Copyright 2015, PayPal under the BSD license.