<script type="text/javascript">

function is_blank(str){

var reg = /^\s+$/;

return reg.test(str);

}

function del_blank(str){

var reg = /\s+/g;

return str.replace(reg,"");

}

var str_1 = " ";

var str_2 = "aa dd gg da";

alert(is_blank(str_1));

alert(del_blank(str_2));

</script>