How to create a Linear Gradient color in echarts 4

echarts4-linear-gradient-color.js

// ...
const color = this._colors[i % this._colors.length];
const colorNext = echarts.color.lift(color, 0.3);

return {
    type: 'linear',
    x: 0,
    y: 1,
    x2: 0,
    y2: 0,
    colorStops: [{
        offset: 0, color: color // color at 0% position
    }, {
        offset: 1, color: colorNext // color at 100% position
    }],
    globalCoord: false // false by default
}
// ...