实现的效果：箭头按弧线的轨迹运行，运行的轨迹为虚线状态，运行到弧线末端后，变成直线运行

HTML代码

<svg width="800px" height="600px" viewbox="0 0 190 150">
    <defs>
        <marker id="markerArrow" markerWidth="6" markerHeight="9" refx="6" refy="5" orient="auto">
            <path d="M0,0 L6,5 L0,9"></path>
        </marker>
    </defs>
    <path id="path" d="M45,0 A60,60 0 0,1 105,60 l70,0" transform="translate(0.5,0.5)" stroke-dasharray="3,3" marker-end="url(#markerArrow)">
    </path>
</svg>

CSS代码

svg {
    margin:50px;
}
path {        
    fill:none;
    stroke:#091631;
    stroke-width:1;    
}

Javascript代码

var obj = document.getElementById('path');
var angle = 0;
var radius = 60;
var line = 0;
var cx, cy, attr;
;(function draw(){
    var req = requestAnimationFrame(draw);
    if(angle < 90){
        cx = 45 + Math.sin(angle * Math.PI/180) * radius;
        cy = 60 - Math.cos(angle * Math.PI/180) * radius;    
        attr = ['M', 45, 0, 'A', 60, 60, 0, 0, 1, cx, cy];   
        angle += 1;
    }else if(line < 70){
        attr = ['M', 45, 0, 'A', 60, 60, 0, 0, 1, cx, cy, 'l', line, 0]; 
        line += 1;
    }else{
        cancelAnimationFrame(req) 
    }
    obj.setAttribute('d',attr.join(' '));
})();

代码很简单，可以举一反三做其它效果。