// JScript 文件
function activeST(num){
    for(var i=1; i<4; i++){
        document.getElementById("searchtype" + i.toString()).className=""; 
    }
    
    document.getElementById("searchtype" + num.toString()).className="so1";
}

document.write('<div><a href="javascript:void(null);" onclick="activeST(1);"><span id="searchtype1" class="so1">按标题</span></a>');
document.write(' <a href="javascript:void(null);" onclick="activeST(2);"><span id="searchtype2">按作者</span></a> ');
document.write('<a href="javascript:void(null);" onclick="activeST(3);"><span id="searchtype3">按正文</span></a></div>');
document.write('<div><input type="text" class="so" /><input type="button" name="button" value="搜索" class="sub" /></div>');