React设置localStorage的过期时间注：思路很简单，存储的值加一个时间戳，下次取值时验证时间戳。localS

注：思路很简单，存储的值加一个时间戳，下次取值时验证时间戳。localStorage只能存储字符，存入时将对象转为json字符串,读取时也要解析

Storage.prototype.setExpire = (key, value, expire) => {
	let obj = {
	data: value,
	time: Date.now(),
	expire: expire
	};
	//localStorage 设置的值不能为对象,转为json字符串
	localStorage.setItem(key, JSON.stringify(obj));
}

Storage.prototype.getExpire = key => {
    let val = localStorage.getItem(key);
    if (!val) {
        return val;
    }
    val = JSON.parse(val);
    if (Date.now() - val.time > val.expire) {
        localStorage.removeItem(key);
        return null;
    }
    return val.data;
}
//将需要的东西存储进去
localStorage.setExpire('userId','zhangsan',5000);
window.setInterval(()=>{
    console.log(localStorage.getExpire("userId"));
},1000)