问用Pixjs修改多边形顶点位置

EN

var el = document.getElementById('slider');

if (el) {
    el.addEventListener('input', changePolygon);
    console.log("Great!!")
}
else{
    console.log("It's null!!")
    throw new ReferenceError("missingElement is not defined");
}

function changePolygon(e){
graphics.clear();
    var target = (e.target) ? e.target : e.srcElement;
    console.log(target.value)

    // draw polygon  
    // flat array of numbers that will be interpreted as [x,y, x,y, ...], 
    let path = [300, 370,
                500, 370,
                500, 420, 
                target.value, 420]; 

    graphics.lineStyle(outline_thicknes, outline_color, 1);
    graphics.beginFill(0x650A5A);
   graphics.drawPolygon(path);
    graphics.endFill();

}