cookie实现本地数据存储

function clear() {
    var exdate = new Date();
    exdate.setTime(exdate.getTime() - 10000);
    document.cookie = "p=0;expires=" + exdate.toGMTString() + ";path=/";
}

function set(p) {
    var exdate = new Date();
    exdate.setTime(exdate.getTime() + (60 * 60 * 1000));
    document.cookie = "p=" + escape(p) + ";expires=" + exdate.toGMTString() + ";path=/";
}

function get() {
    var p = "";
    var c_name = "p";
    if (document.cookie.length > 0) {
        var c_start = document.cookie.indexOf(c_name + "=");
        if (c_start != -1) {
            c_start = c_start + c_name.length + 1;
            var c_end = document.cookie.indexOf(";", c_start);
            if (c_end == -1) c_end = document.cookie.length;
            P = unescape(document.cookie.substring(c_start, c_end))
        }
    }

    if (p == "" || p == null) {
        p = prompt("请输入：");
    }

    return p;
}