根据点的符号改变线颜色的解决方案已经通过将borderColor设置为segment s来实现，并且对于具有相同符号的两端的所有段都工作良好;配置对象为

datasets:[{
    data: ....
    .......
    segment: {
        borderColor: (ctx) => {
            return getBorderColor(ctx);
        }
    },
}]

实际的计算在函数getBorderColor中实现（从原始的稍微修改，以简化下面我的扩展的介绍）：

const getBorderColor = 
        (ctx, colPositive = "green", colNegative = "red") => {
    return ctx.p0.parsed.y >= 0 ? colPositive : colNegative;
};

为了适应与x轴相交的线段，我找到的解决方案是将颜色设置为LinearGradient，其中有四个color stops，如下表所示：

point:    p0       x-axis intersection      p1
coordinates:  (x0, y0)        (_, 0)           (x1, y1)
   fraction:     0             frac               1
      color:   green ------> green|red --------> red

其中frac很容易从两点的坐标计算。可以看出，这实际上不是视觉梯度，颜色从“绿色”到“红色”的变化（用作示例）是在同一点完成的，即线段与x轴的交点。
下面是代码，注解中有解释：

const getBorderColor = (ctx, colPositive = "green", colNegative = "red") => {
    if (ctx.p0.parsed.y * ctx.p1.parsed.y < 0) {
        // if the segment changes sign from p0 to p1
        const x0 = ctx.p0.parsed.x,
            x1 = ctx.p1.parsed.x,
            y0 = ctx.p0.parsed.y,
            y1 = ctx.p1.parsed.y,
            dataset = ctx.chart.data.datasets[ctx.datasetIndex],
            //identify the correct axes used for the dataset
            xAxisId = dataset.xAxisId ?? "x",
            yAxisId = dataset.yAxisId ?? "y",
            //transform values to pixels
            x0px = ctx.chart.scales[xAxisId].getPixelForValue(x0),
            x1px = ctx.chart.scales[xAxisId].getPixelForValue(x1),
            y0px = ctx.chart.scales[yAxisId].getPixelForValue(y0),
            y1px = ctx.chart.scales[yAxisId].getPixelForValue(y1);
        
        // create gradient form p0 to p1
        const gradient = ctx.chart.ctx.createLinearGradient(x0px, y0px, x1px, y1px);
        // calculate frac - the relative length of the portion of the segment
        // from p0 to the point where the segment intersects the x axis
        const frac = Math.abs(y0) / (Math.abs(y0) + Math.abs(y1));
        // set colors at the ends of the segment
        const [col_p0, col_p1] =
            y0 > 0 ? [colPositive, colNegative] : [colNegative, colPositive];
        gradient.addColorStop(0, col_p0);
        gradient.addColorStop(frac, col_p0);
        gradient.addColorStop(frac, col_p1);
        gradient.addColorStop(1, col_p1);
        return gradient;
    }
    return ctx.p0.parsed.y >= 0 ? colPositive : colNegative;
};

和原始codesandbox的the fork。