javascript的onbeforeunload函数在IOS上运行
今天在做项目的时候,组长让我用iPad测试一下前面写的离线缓存,后退不刷新页面,发现在iPad上onbeforeunload函数在iPad上一带而过,不运行???
无奈之下,发现原来在IOS上,有自己的onshow和onhide方法 //搜索来自:http://www.cnblogs.com/vaal-water/archive/2012/09/25/2701769.html
原文如下:
window.addEventListener("pageshow", myLoadHandler, false); window.addEventListener("pagehide", myUnloadHandler, false);
function myLoadHandler(evt) { if (evt.persisted) { // This is actually a pageshow event and the page is coming out of the Page Cache. // Make sure to not perform the "one-time work" that we'd normally do in the onload handler. ... return; } // This is either a load event for older browsers, // or a pageshow event for the initial load in supported browsers. // It's safe to do everything my old load event handler did here. ... } function myUnloadHandler(evt) { if (evt.persisted) { // This is actually a pagehide event and the page is going into the Page Cache. // Make sure that we don't do any destructive work, or work that shouldn't be duplicated. ... return; } // This is either an unload event for older browsers, // or a pagehide event for page tear-down in supported browsers. // It's safe to do everything my old unload event handler did here. ... } if ("onpagehide" in window) { window.addEventListener("pageshow", myLoadHandler, false); window.addEventListener("pagehide", myUnloadHandler, false); } else { window.addEventListener("load", myLoadHandler, false); window.addEventListener("unload", myUnloadHandler, false); } 原文 http://www.webkit.org/blog/516/webkit-page-cache-ii-the-unload-event/
我自己的程序如下:
先写了一个判断是不是IOS系统的方法:
function isIOS() {
var userAgentInfo = navigator.userAgent;
var Agents = [ "iPhone","iPad"];
var flag = false;
for (var v = 0; v < Agents.length; v++) {
if (userAgentInfo.indexOf(Agents[v]) > 0) {
flag = true;
break;
}
}
return flag;
}
等于这个:
var nav = window.navigator.userAgent.toLowerCase();
var ipad = nav.indexOf("ipad");
我的理解是:
当页面加载完的时候给window加载监听器
window.addEventListener("pagehide", myUnloadHandler, false);
window.addEventListener("pageshow", myLoadHandler, false);
系统自动识别是不是IOS系统,然后做出处理
if(!parent.isIOS()){} //或者是if(ipad != -1){}
当IOS系统加载的时候,执行myloadHandler函数(相当于js的onload函数),当离开页面的时候执行myUnloadHandler函数(相当于js的onbeforeunload函数),
然后在myloadHandler函数中做出你要执行的加载页面时触发的事件,在myUnloadHandler函数中做出你要离开页面时触发的事件
全部代码以及冗余代码如下:没有删减
var nav = window.navigator.userAgent.toLowerCase();
alert(nav);
var ipad = nav.indexOf("ipad");
alert(parent.isIOS());
if(!parent.isIOS()){
alert("ipad");
alert("SUCCESS");
window.addEventListener("pagehide", myUnloadHandler, false);
/* window.addEventListener("pageshow", myLoadHandler, false);
function myLoadHandler(evt)
{
alert("myLoadHandler");
start = parseInt(sessionStorage.getItem("start"+token));
paramFlag = sessionStorage.getItem("paramFlag"+token);
tokenDiv = sessionStorage.getItem("tokenDiv"+token);
//$("#tokenDiv").html(tokenDiv); 由于放在sessionstorage中的div的id都一样,故吧时间戳作为唯一标识ID
$("#tokenDiv").html(tokenDiv);
} */
function myUnloadHandler(evt)
{
alert("myUnloadHandler");
alert("离开页面了");
var tokenDiv = $("#tokenDiv").html();
sessionStorage.setItem("tokenDiv"+token,tokenDiv);
sessionStorage.setItem("start"+token,start);
sessionStorage.setItem("paramFlag"+token,paramFlag);
}
}
window.onbeforeunload = function(){
alert("离开页面了");
var tokenDiv = $("#tokenDiv").html();
sessionStorage.setItem("tokenDiv"+token,tokenDiv);
sessionStorage.setItem("start"+token,start);
sessionStorage.setItem("paramFlag"+token,paramFlag);
/* if ("onpagehide" in window) {
alert("one");
window.addEventListener("pageshow", myLoadHandler, false);
window.addEventListener("pagehide", myUnloadHandler, false);
} else {
alert("two");
window.addEventListener("load", myLoadHandler, false);
window.addEventListener("unload", myUnloadHandler, false);
} */
}