Javascript-форум - Доработать скрипт

Нужно что бы анимация запускать когда человек в нужном блоке.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Untitled Page</title>
<style type="text/css">
.anim-1 {
stroke-dasharray: 1000;
stroke-dashoffset: 1000;
animation: dash 2.5s linear alternate forwards ;
}

@keyframes dash {
0% {
stroke-dashoffset: 1000;
}

90% {
fill-opacity: 0;
}

100% {
stroke-dashoffset: 0;
fill-opacity: 1;
}
}

.anim-2 {
stroke-dasharray: 1000;
stroke-dashoffset: 1000;
animation: dash2 4.5s linear alternate forwards ;
}

@keyframes dash2 {
0% {
fill-opacity: 0;
}

50% {
fill-opacity: 0;
stroke-dashoffset: 1000;
}

100% {
stroke-dashoffset: 0;
fill-opacity: 1;
}
}
</style>
<script type="text/javascript">
function goSVG() {
var buff = document.getElementById('svgBlock');
buff.innerHTML = buff.innerHTML;

}
</script>
</head>
<body onscroll="goSVG();">
<div id="svgBlock">
<svg width="450px" height="160px">
<text id="svgText" class="anim-1" x="0" y="158px" font-size="200px" stroke="#222121" stroke-width="1" fill-opacity="0">WEB</text>
</svg>
<svg width="300px" height="20px">
<line class="anim-2" fill-opacity="0" stroke="#000" stroke-width="1" x1="20" x2="300" y1="18" y2="18"/>
</svg>
</div>
</body>
</html>