配列要素を抜き出すには
<html>
<head>
<title>Sample</title>
</head>
<body>
<script type="text/javascript"><!--
colorName = ["黒色","青色","赤色","紫色","緑色","水色","黄色","白色"];
ary1 = colorName.slice(3,6);
document.write(ary1,"<br>");
ary2 = colorName.splice(2,1,"ブラック");
document.write(ary2,"<br>");
document.write(colorName,"<br>");
// --></script>
</body>
</html>
説明などは本書を参考にしてください。