html只显示一次,JavaScript让提示信息只出现一次

51前端

var alertmessage = "51前端欢迎您"

var once_per_session = 1

function get_cookie(Name) {

var search = Name + "=";

var returnvalue = "";

if (document.cookie.length > 0) {

offset = document.cookie.indexOf(search)

if (offset != -1) {

offset += search.length

end = document.cookie.indexOf(";", offset);

if (end == -1) {

end = document.cookie.length;

returnvalue = unescape(document.cookie.substring(offset, end))

}

}

}

return returnvalue;

}

function alertornot() {

if (get_cookie('alerted') == '') {

loadalert()

document.cookie = "alerted=yes"

}

}

function loadalert() {

alert(alertmessage)

}

if (once_per_session == 0) {

loadalert()

} else {

alertornot()

}