SOURCE

var times = 's60';
var key ='token';
var value = '123';
var strsec = get_sec(times);
                var exp = new Date();
                exp.setTime(exp.getTime() + strsec * 1);
                document.cookie = key + "=" + escape(value) + ";expires=" + exp.toGMTString() + ';path=/';

                 function get_sec(str) {
                var str1 = str.substring(1, str.length) * 1;
                var str2 = str.substring(0, 1);
                if (str2 == "s") {
                    return str1 * 1000;
                } else if (str2 == "h") {
                    return str1 * 60 * 60 * 1000;
                } else if (str2 == "d") {
                    return str1 * 24 * 60 * 60 * 1000;
                }
            }