var str = "$6,117,766.69";
var nonNumber = "$,.";

for (var i = 0; i < str.length; i++) {
    if (nonNumber.contains(str[i])) {
        $('body').append("<span class = 'thecolorYellow'>"+str[i]+"</span>");
    } else {
        $('body').append("<span class = 'thecolorBlue'>"+str[i]+"</span>");
    }
}