设置localStorage的过期时间

/**
 *
 * @param key
 * @param value
 * @param exp  有效期
 */
function mySetLocalStorage(key, value, exptime = 0) {
    var nowtime = new Date().getTime()/1000; // 获取当前时间 ，转换成JSON字符串序列
    if(exptime == 0){
        exptime = nowtime + 60*10; //默认10分钟有效期
    }
    var valueDate = JSON.stringify({
        val: value,
        exptime: exptime
    });
    try {
        localStorage.setItem(key, valueDate);
    } catch(e) {
        /*if(e.name === 'QUOTA_EXCEEDED_ERR' || e.name === 'NS_ERROR_DOM_QUOTA_REACHED') {
            console.log("Error: 本地存储超过限制");
            localStorage.clear();
        } else {
            console.log("Error: 保存到本地存储失败");
        }*/
        // 兼容性写法
        if(myIsQuotaExceeded(e)) {
            console.log("Error: 本地存储超过限制");
            localStorage.clear();
        } else {
            console.log("Error: 保存到本地存储失败");
        }
    }
}

function myIsQuotaExceeded(e) {
    var quotaExceeded = false;
    if(e) {
        if(e.code) {
            switch(e.code) {
                case 22:
                    quotaExceeded = true;
                    break;
                case 1014: // Firefox
                    if(e.name === 'NS_ERROR_DOM_QUOTA_REACHED') {
                        quotaExceeded = true;
                    }
                    break;
            }
        } else if(e.number === -2147024882) { // IE8
            quotaExceeded = true;
        }
    }
    return quotaExceeded;
}

function myGetLocalStorage(key) {
    if(localStorage.getItem(key)) {
        var vals = localStorage.getItem(key); // 获取本地存储的值
        var dataObj = JSON.parse(vals); // 将字符串转换成JSON对象
        // 如果(当前时间 - 存储的元素在创建时候设置的时间) > 过期时间
        var isTimed = (new Date().getTime()/1000 - dataObj.exptime) > 0;
        if(isTimed) {
            console.log("存储已过期");
            localStorage.removeItem(key);
            return null;
        } else {
            var newValue = dataObj.val;
        }
        return newValue;
    } else {
        return null;
    }
}

mySetLocalStorage('name', 'hello, world');
var localKey = myGetLocalStorage('name');
console.log(localKey);