What are some best practices for designing and testing Ext JS charts for different devices and browsers?

1 Choose the right chart type

The first step in designing Ext JS charts is to choose the right chart type for your data and your audience. Ext JS offers a variety of chart types, such as line, bar, pie, radar, scatter, gauge, and more. Each chart type has its own advantages and disadvantages, depending on the type, size, and distribution of your data, as well as the message you want to convey. For example, line charts are good for showing trends over time, while pie charts are good for showing proportions of a whole. You should also consider the readability and aesthetics of your chart type, and avoid using too many colors, labels, or series that can clutter your chart or confuse your viewers.

2 Use responsive layouts and configs

The next step in designing Ext JS charts is to use responsive layouts and configs to ensure that your charts adapt to different screen sizes and orientations. Ext JS provides a responsive plugin that allows you to define rules and conditions for your chart components based on the viewport width, height, or orientation. For example, you can use the responsive plugin to change the position, size, or visibility of your chart legend, axes, or labels depending on the available space. You can also use the flex config to make your chart components grow or shrink proportionally to their container. Additionally, you can use media queries and CSS to customize the style and appearance of your charts for different devices and browsers.

3 Optimize the performance and memory

The third step in designing Ext JS charts is to optimize the performance and memory of your charts, especially if you are dealing with large or dynamic data sets. Ext JS charts use a drawing engine called Sencha Draw that renders your charts using SVG or Canvas, depending on the browser support and the chart type. SVG is a vector-based format that allows you to scale and manipulate your charts without losing quality, while Canvas is a bitmap-based format that allows you to draw complex and animated charts with high performance. However, both formats have their limitations and trade-offs, such as memory consumption, rendering speed, and event handling. Therefore, you should choose the best format for your chart type and data set, and use the enginePriority config to specify your preferred drawing engine. You should also use the enableShadows and useDarkerStrokeColor configs to disable or reduce the shadow and stroke effects on your charts, as they can affect the performance and memory of your charts.

4 Test your charts on different devices and browsers

The final step in designing Ext JS charts is to test your charts on different devices and browsers to ensure that they work as expected and look consistent. Ext JS charts are cross-browser compatible, meaning that they can run on most modern browsers, such as Chrome, Firefox, Safari, Edge, and IE11. However, there may be some minor differences or issues in how your charts are rendered or interacted with on different browsers, due to the different implementations and standards of the drawing engines and the browser APIs. Therefore, you should test your charts on different devices and browsers using tools such as BrowserStack, Sauce Labs, or Sencha Test, which allow you to simulate and automate your testing scenarios on various platforms and environments. You should also check the accessibility and usability of your charts on different devices and browsers, such as the keyboard navigation, touch gestures, screen reader support, and color contrast.