我有JavaScript，它周期性地执行活动。当用户没有在看站点时(例如，窗口或选项卡没有焦点)，最好不要运行。
是否有一种方法可以使用JavaScript来做到这一点?
我的参考点:如果你正在使用的窗口不活跃，Gmail聊天就会播放声音。
当前回答
我重读了@daniel-buckmaster的版本 我没有做多次尝试，但是，代码对我来说似乎更优雅…
// on-visibility-change.js v1.0.1, based on https://stackoverflow.com/questions/1060008/is-there-a-way-to-detect-if-a-browser-window-is-not-currently-active#38710376
function onVisibilityChange(callback) {
let d = document;
let visible = true;
let prefix;
if ('hidden' in d) {
prefix = 'h';
} else if ('webkitHidden' in d) {
prefix = 'webkitH';
} else if ('mozHidden' in d) {
prefix = 'mozH';
} else if ('msHidden' in d) {
prefix = 'msH';
} else if ('onfocusin' in d) { // ie 9 and lower
d.onfocusin = focused;
d.onfocusout = unfocused;
} else { // others
window.onpageshow = window.onfocus = focused;
window.onpagehide = window.onblur = unfocused;
};
if (prefix) {
visible = !d[prefix + 'idden'];
d.addEventListener(prefix.substring(0, prefix.length - 1) + 'visibilitychange', function() {
(d[prefix + 'idden'] ? unfocused : focused)();
});
};
function focused() {
if (!visible) {
callback(visible = true);
};
};
function unfocused() {
if (visible) {
callback(visible = false);
};
};
};
其他回答
这是根据安迪?
这将执行一个任务，例如每30秒刷新一次页面， 但前提是页面是可见的和集中的。
如果无法检测到可见性，则只使用焦点。
如果用户聚焦页面，那么它将立即更新
页面直到ajax调用后30秒才会再次更新
var windowFocused = true;
var timeOut2 = null;
$(function(){
$.ajaxSetup ({
cache: false
});
$("#content").ajaxComplete(function(event,request, settings){
set_refresh_page(); // ajax call has just been made, so page doesn't need updating again for 30 seconds
});
// check visibility and focus of window, so as not to keep updating unnecessarily
(function() {
var hidden, change, vis = {
hidden: "visibilitychange",
mozHidden: "mozvisibilitychange",
webkitHidden: "webkitvisibilitychange",
msHidden: "msvisibilitychange",
oHidden: "ovisibilitychange" /* not currently supported */
};
for (hidden in vis) {
if (vis.hasOwnProperty(hidden) && hidden in document) {
change = vis[hidden];
break;
}
}
document.body.className="visible";
if (change){ // this will check the tab visibility instead of window focus
document.addEventListener(change, onchange,false);
}
if(navigator.appName == "Microsoft Internet Explorer")
window.onfocus = document.onfocusin = document.onfocusout = onchangeFocus
else
window.onfocus = window.onblur = onchangeFocus;
function onchangeFocus(evt){
evt = evt || window.event;
if (evt.type == "focus" || evt.type == "focusin"){
windowFocused=true;
}
else if (evt.type == "blur" || evt.type == "focusout"){
windowFocused=false;
}
if (evt.type == "focus"){
update_page(); // only update using window.onfocus, because document.onfocusin can trigger on every click
}
}
function onchange () {
document.body.className = this[hidden] ? "hidden" : "visible";
update_page();
}
function update_page(){
if(windowFocused&&(document.body.className=="visible")){
set_refresh_page(1000);
}
}
})();
set_refresh_page();
})
function get_date_time_string(){
var d = new Date();
var dT = [];
dT.push(d.getDate());
dT.push(d.getMonth())
dT.push(d.getFullYear());
dT.push(d.getHours());
dT.push(d.getMinutes());
dT.push(d.getSeconds());
dT.push(d.getMilliseconds());
return dT.join('_');
}
function do_refresh_page(){
// do tasks here
// e.g. some ajax call to update part of the page.
// (date time parameter will probably force the server not to cache)
// $.ajax({
// type: "POST",
// url: "someUrl.php",
// data: "t=" + get_date_time_string()+"&task=update",
// success: function(html){
// $('#content').html(html);
// }
// });
}
function set_refresh_page(interval){
interval = typeof interval !== 'undefined' ? interval : 30000; // default time = 30 seconds
if(timeOut2 != null) clearTimeout(timeOut2);
timeOut2 = setTimeout(function(){
if((document.body.className=="visible")&&windowFocused){
do_refresh_page();
}
set_refresh_page();
}, interval);
}
我重读了@daniel-buckmaster的版本 我没有做多次尝试，但是，代码对我来说似乎更优雅…
// on-visibility-change.js v1.0.1, based on https://stackoverflow.com/questions/1060008/is-there-a-way-to-detect-if-a-browser-window-is-not-currently-active#38710376
function onVisibilityChange(callback) {
let d = document;
let visible = true;
let prefix;
if ('hidden' in d) {
prefix = 'h';
} else if ('webkitHidden' in d) {
prefix = 'webkitH';
} else if ('mozHidden' in d) {
prefix = 'mozH';
} else if ('msHidden' in d) {
prefix = 'msH';
} else if ('onfocusin' in d) { // ie 9 and lower
d.onfocusin = focused;
d.onfocusout = unfocused;
} else { // others
window.onpageshow = window.onfocus = focused;
window.onpagehide = window.onblur = unfocused;
};
if (prefix) {
visible = !d[prefix + 'idden'];
d.addEventListener(prefix.substring(0, prefix.length - 1) + 'visibilitychange', function() {
(d[prefix + 'idden'] ? unfocused : focused)();
});
};
function focused() {
if (!visible) {
callback(visible = true);
};
};
function unfocused() {
if (visible) {
callback(visible = false);
};
};
};
从最初编写这个答案开始，由于W3C，一个新的规范已经达到了推荐状态。页面可见性API(在MDN上)现在允许我们更准确地检测页面何时对用户隐藏。
document.addEventListener("visibilitychange", onchange);
当前浏览器支持:
铬13 + Internet Explorer 10+ Firefox 10 + Opera 12.10+[阅读笔记]
下面的代码在不兼容的浏览器中退回到不太可靠的模糊/聚焦方法:
(function() {
var hidden = "hidden";
// Standards:
if (hidden in document)
document.addEventListener("visibilitychange", onchange);
else if ((hidden = "mozHidden") in document)
document.addEventListener("mozvisibilitychange", onchange);
else if ((hidden = "webkitHidden") in document)
document.addEventListener("webkitvisibilitychange", onchange);
else if ((hidden = "msHidden") in document)
document.addEventListener("msvisibilitychange", onchange);
// IE 9 and lower:
else if ("onfocusin" in document)
document.onfocusin = document.onfocusout = onchange;
// All others:
else
window.onpageshow = window.onpagehide
= window.onfocus = window.onblur = onchange;
function onchange (evt) {
var v = "visible", h = "hidden",
evtMap = {
focus:v, focusin:v, pageshow:v, blur:h, focusout:h, pagehide:h
};
evt = evt || window.event;
if (evt.type in evtMap)
document.body.className = evtMap[evt.type];
else
document.body.className = this[hidden] ? "hidden" : "visible";
}
// set the initial state (but only if browser supports the Page Visibility API)
if( document[hidden] !== undefined )
onchange({type: document[hidden] ? "blur" : "focus"});
})();
ie9及以下版本需要onfocusin和onfocusout，而所有其他都使用onfocus和onblur，除了iOS，它使用onpageshow和onpagehide。
如果你想对整个浏览器模糊: 正如我所评论的，如果浏览器失去焦点，建议的事件都不会触发。我的想法是在循环中计数，并在事件发生时重置计数器。如果计数器达到限制，我做一个位置。请转到另一页。如果你在开发工具上工作，这也会触发。
var iput=document.getElementById("hiddenInput");
,count=1
;
function check(){
count++;
if(count%2===0){
iput.focus();
}
else{
iput.blur();
}
iput.value=count;
if(count>3){
location.href="http://Nirwana.com";
}
setTimeout(function(){check()},1000);
}
iput.onblur=function(){count=1}
iput.onfocus=function(){count=1}
check();
这是在FF上成功测试的草稿。
这适用于所有现代浏览器:
更改制表符时 更改窗口时(Alt+Tab) 当从任务栏最大化另一个程序时
var eventName;
var visible = true;
var propName = "hidden";
if (propName in document) eventName = "visibilitychange";
else if ((propName = "msHidden") in document) eventName = "msvisibilitychange";
else if ((propName = "mozHidden") in document) eventName = "mozvisibilitychange";
else if ((propName = "webkitHidden") in document) eventName = "webkitvisibilitychange";
if (eventName) document.addEventListener(eventName, handleChange);
if ("onfocusin" in document) document.onfocusin = document.onfocusout = handleChange; //IE 9
window.onpageshow = window.onpagehide = window.onfocus = window.onblur = handleChange;// Changing tab with alt+tab
// Initialize state if Page Visibility API is supported
if (document[propName] !== undefined) handleChange({ type: document[propName] ? "blur" : "focus" });
function handleChange(evt) {
evt = evt || window.event;
if (visible && (["blur", "focusout", "pagehide"].includes(evt.type) || (this && this[propName]))){
visible = false;
console.log("Out...")
}
else if (!visible && (["focus", "focusin", "pageshow"].includes(evt.type) || (this && !this[propName]))){
visible = true;
console.log("In...")
}
}
