javascript - 如何检测移动到 Mobile Safari 中的新选项卡

Question

我想知道如何在 iOS 7 上的移动 safari 中获得相当于 $(window).blur 事件的功能。我希望这样做是为了检测选项卡何时不存在屏幕上的时间更长。之前已经问过几次了( Detect moving to a new tab in Mobile Safari )，但是，所有答案要么不再起作用，要么只给出 $(window).focus 事件，而不是 $ (window).blur 事件。另外，$(window).blur 会在 safari 关闭时触发吗？

Answer 1

根据这篇文章:http://www.mobilexweb.com/blog/safari-ios7-html5-problems-apis-review

Page Visibility is the API -webkit-prefixed on iOS 7- to detect when our tab goes foreground and background. XMLHttpRequest 2.0 spec fully compatible means that now we can request ‘blob’ as a response. The Video tracks API was already covered quickly and it allow us to query and navigate through all the tracks and contents on any media element.

实现其基本演示的相关代码如下所示；希望您可以对其进行调整以满足您的要求。这是一个很好的示例，因为它不仅向您展示了如何捕获状态更改，还展示了如何在 visibilityChanged 事件期间请求数据:

var eventName = "visibilitychange";
if (document.webkitHidden != undefined) {
    eventName = "webkitvisibilitychange";
    document.write("<h2>webkit prefix detected</h2>");
} else if (document.mozHidden != undefined) {
    eventName = "mozvisibilitychange";
    document.write("<h2>moz prefix detected</h2>");
} else if (document.msHidden != undefined) {
    eventName = "msvisibilitychange";
    document.write("<h2>MS prefix detected</h2>");
} else if (document.hidden != undefined) {
    document.write("<h2>standard API detected</h2>");
} else {
    document.write("<h2>API not available</h2>");
}


function visibilityChanged() {
    var h4 = document.getElementsByTagName("h4")[0];
    if (document.hidden || document.mozHidden || document.msHidden || document.webkitHidden) {
        h4.innerHTML += "<br>Hidden at " + Date().toString();
        var ajax = new XMLHttpRequest();
        ajax.open("GET", "sleep.php?" + Math.random(), true);
        ajax.onreadystatechange = function () {
            if (ajax.status == 200 && ajax.readyState == 4) {
                h4.innerHTML += "<br>AJAX Async at " + Date().toString();
            }
        }
        ajax.send(null);

        var ajaxs = new XMLHttpRequest();
        ajax.open("GET", "sleep.php?" + Math.random(), false);
        ajax.send(null);
        h4.innerHTML += "<br>AJAX Sync at " + Date().toString();

        setTimeout(function () {
            h4.innerHTML += "<br>Timer at " + Date().toString();
        }, 3000);

    } else {
        h4.innerHTML += "<br>Shown at " + Date().toString();
    }
}
document.addEventListener(eventName, visibilityChanged, false);

window.onpageshow = function () {
    h4.innerHTML = "<br>Page show at " + Date().toString();
};

window.onpagehide = function () {
    h4.innerHTML = "<br>Page hide at " + Date().toString();
};

如果您想在自己的设备上测试它，请观看现场演示:http://mobilexweb.com/ts/api/page.html

当选项卡失去并重新获得焦点时，您将看到写入页面的日志。