我不知道epub3，也没有要测试的MAC，但我想到了四种可能的解决方案：
Cookies
对于该用例，它的性能不如 localStorage，但如果您没有太多选择，总比没有好。
创建、读取和删除 cookie 的函数（致 https://stackoverflow.com/a/28230846/9150652）：
function setCookie(name,value,days) {
var expires = "";
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days*24*60*60*1000));
expires = "; expires=" + date.toUTCString();
}
document.cookie = name + "=" + (value || "") + expires + "; path=/";
}
function getCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function eraseCookie(name) {
document.cookie = name+'=; Max-Age=-99999999;';
}
你的例子的用法：
<script>
//<![CDATA[
var current_page = "1";
var other_page = "2";
var t = 0;
setInterval(function() {
var d = new Date();
setCookie("t"+ current_page, d.toLocaleString(), 100); // 100 days
document.getElementById("result").innerHTML = getCookie("t"+ current_page) +" "+getCookie("t"+ other_page);
}, 1000);
//]]>
</script>
广播频道
BroadcastChannel 是一项非常新的功能，因此“图书”应用可能不支持它。但这里有一个概念：
<script>
//<![CDATA[
var broadcaster = new BroadcastChannel('test');
var current_page = "1";
var other_page = "2";
var t = 0;
setInterval(function() {
var d = new Date();
// Send message to all other tabs with BroadcastChannel('test')
bc.postMessage({
senderPage: "t"+ current_page,
date: d.toLocaleString()
});
}, 1000);
broadcaster.onmessage = (result) => {
if(result.senderPage == "t"+ other_page) { // If the message is from the other page
// Set HTML to current date + sent Date from other page
var d = new Date();
document.getElementById("result").innerHTML = d.toLocaleString() +" "+result.date;
}
};
//]]>
</script>
某种后端
如果上述方法都不起作用，您可能别无选择，只能使用某种后端来提供和保存数据
如果只适合您，我建议您使用 Firebase 或 MongoDB Atlas 的免费层，因为它们都在其免费层上提供了相当多的价值。
如果你用后端来做，它可以用这样的东西来做：
<script>
//<![CDATA[
var current_page = "1";
var other_page = "2";
var lastLocalDate = new Date();
const serverUrl = "http://someUrl.com/endpoint/"
// Gets the latest date of the other page via ajax
function getUpdate() {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE) {
// If successful, update HTML
if (xmlhttp.status == 200) {
document.getElementById("result").innerHTML = lastLocalDate.toLocaleString() +" "+xhr.responseText;
}
// Update the date of this page anyways
sendUpdate();
}
};
// GET request with parameter requestingPage, which is the other page
xmlhttp.open("GET", serverUrl, true);
xmlhttp.send(`requestingPage=${other_page}`);
}
// Sends the current date of this page to the webserver
function sendUpdate() {
var xmlhttp = new XMLHttpRequest();
// No need to check if successful, just update the page again
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE) {
getUpdate();
}
};
lastLocalDate = new Date();
// POST request with parameters page and date
xmlhttp.open("POST", serverUrl, true);
xmlhttp.send(`sendingPage=${current_page}&data=${lastLocalDate.toLocaleString()}`);
}
// Start with sending an update (so that lastLocalDate is at least sent once to the server)
sendUpdate();
//]]>
</script>
您的后端中的一些方法需要看起来像这样（请注意，这不是任何语言的有效代码）：
@GET
function getDate(requestingPageId)
find latest entry with page.id == requestingPageId
return page.date
@POST
function saveDate(savingPage, savingDate)
store new page element with
page.id = savingPage
page.date = savingDate
您的数据库中的集合如下所示：
[
{
id: 1,
date: "date"
},{
id: 2,
date: "date"
},{
id: 2,
date: "date"
},{
id: 1,
date: "date"
},
// ...
]
窗口引用
如果图书应用从第一个选项卡打开第二个选项卡，则可能值得研究一下：