Js存储数据到LocalStorage并设置过期时间

 setLocal = function (key, val) {
        var prefix = "project_list_";
        key = prefix + key;
        var expires = 600;
        val = JSON.stringify({'val': val, 'expires': new Date().getTime() + expires * 1000});
        localStorage.setItem(key, val);
    };

    getLocal = function (key) {
        var prefix = "project_list_";
        key = prefix + key;
        var val = localStorage.getItem(key);
        if (!val) {
            return null;
        }
        val = JSON.parse(val);
        if (val.expires < new Date().getTime()) {
            localStorage.removeItem(key);
            return null;
        }
        return val.val;
    };