Implement gradient color in jointjs

Quick answer：

JointJS is a powerful and flexible JavaScript library for creating interactive diagrams and workflows. To implement gradient color in JointJS, you can utilize the 'fill' property of the shape's CSS style. This property accepts a gradient CSS value. You can define linear gradients using the 'linear-gradient' function, specifying the colors and their positions along the gradient line. For example: 'fill': 'linear-gradient(to right, red, yellow)'. For more advanced gradient styles, consider using SVG gradients within the shape's SVG markup.