check

String.prototype.trim = function (c) {

if (!c) c = "\\s";

return this.replace(new RegExp("(^" + c + "+)|(" + c + "+$)", "ig"), "");

};

function chkTag(e) {

var val = "";

if (e.checked) {

val = $("#txtTag").val().trim(',').trim('，') + ',' + $(e).next().text();

val = val.trim(',').trim('，');

} else {

val = $("#txtTag").val().replace(new RegExp("(^|[,，])(" + $(e).next().text().replace(/([()])/g,'\\$1') + ")([,，]|$)", "ig"), function (all, s1, s2, s3) {

return (s1 && s3) ? s1 : '';

});

}

$("#txtTag").val(val.trim(','));

}