これが1つの方法です:http:
//jsfiddle.net/VTp4D/
SVGファイルの関連部分:
<path id="busTrack2" ...>
<animate id="dashAnim2" attributeName="stroke-dashoffset" from="0"
to="0" dur="10s" begin="0" fill="freeze" keySplines="0 0.5 0.5 1"
calcMode="spline"/>
</path>
Javascriptコード:
var busTrack = document.getElementById('busTrack2');
var busTrackAnim = document.getElementById('dashAnim2');
var trackLength = busTrack.getTotalLength().toString();
busTrack.setAttribute('stroke-dasharray',trackLength+','+trackLength);
// forward:
// busTrackAnim.setAttribute('values',trackLength+';0');
// backward:
busTrackAnim.setAttribute('values','-'+trackLength+';0');