function drawArrow(ctx,x1,y1,x2,y2,arrowLength,arrowWidth){const dx=x2-x1;const dy=y2-y1;const len=Math.sqrt(dx*dx+dy*dy);const perc=(len-arrowLength)/len;const bx=x1+perc*dx;const by=y1+perc*dy;const ux=dx/len;const uy=dy/len;const ax=uy*arrowWidth;const ay=-ux*arrowWidth;ctx.beginPath();drawLine(ctx,x1,y1,x2,y2);ctx.stroke();drawTriangle(ctx,bx+ax,by+ay,x2,y2,bx-ax,by-ay);ctx.fill();}