small selector testing function (would like to get it down to 140 bytes)

is.js

function is(a,b,c,d){
    b=(!(c=(d=b.split(".")).shift().split("#"))[0]||a.nodeName==c[0].toUpperCase())&&
        (!c[1]||a.id==c[1])
    for(c=d.length;b=b&&~(' '+a.className+' ').indexOf(' '+d[--c]+' '););
    return b;
}