检测浏览器标签是否有焦点

是否有一种可靠的跨浏览器方法来检测标签是否有焦点。

这个场景是，我们有一个定期轮询股票价格的应用程序，如果页面没有焦点，我们可以停止轮询并节省所有人的交通噪音，特别是当人们喜欢打开不同投资组合的几个选项卡时。

window.onblur和window.onfocus是一个选项吗?

181664 次浏览
小开

这个答案已经过时了。写完之后，能见度API (中数， 例子， 规范)就被引入了。这是解决这个问题更好的办法。

var focused = true;


window.onfocus = function() {
focused = true;
};
window.onblur = function() {
focused = false;
};

AFAIK， focus和blur都支持…所有东西。(参见http://www.quirksmode.org/dom/events/index.html)

小开
最佳答案

是的，window.onfocus和window.onblur应该适用于您的场景:

http://www.thefutureoftheweb.com/blog/detect-browser-window-focus < a href = " http://www.thefutureoftheweb.com/blog/detect-browser-window-focus " > < / >

小开

在搜索这个问题时，我发现应该使用页面可见性API的建议。大多数现代浏览器根据Can I Use: http://caniuse.com/#feat=pagevisibility支持此API。

下面是一个工作示例(来自这个代码片段):

$(document).ready(function() {
var hidden, visibilityState, visibilityChange;


if (typeof document.hidden !== "undefined") {
hidden = "hidden", visibilityChange = "visibilitychange", visibilityState = "visibilityState";
} else if (typeof document.msHidden !== "undefined") {
hidden = "msHidden", visibilityChange = "msvisibilitychange", visibilityState = "msVisibilityState";
}


var document_hidden = document[hidden];


document.addEventListener(visibilityChange, function() {
if(document_hidden != document[hidden]) {
if(document[hidden]) {
// Document hidden
} else {
// Document shown
}


document_hidden = document[hidden];
}
});
});

上面的例子曾经为Gecko和WebKit浏览器提供前缀属性，但我删除了这个实现，因为这些浏览器已经提供了一段时间没有前缀的页面可见性API。为了与IE10兼容，我保留了微软特有的前缀。

小开

我会这样做(参考http://www.w3.org/TR/page-visibility/):

    window.onload = function() {


// check the visiblility of the page
var hidden, visibilityState, visibilityChange;


if (typeof document.hidden !== "undefined") {
hidden = "hidden", visibilityChange = "visibilitychange", visibilityState = "visibilityState";
}
else if (typeof document.mozHidden !== "undefined") {
hidden = "mozHidden", visibilityChange = "mozvisibilitychange", visibilityState = "mozVisibilityState";
}
else if (typeof document.msHidden !== "undefined") {
hidden = "msHidden", visibilityChange = "msvisibilitychange", visibilityState = "msVisibilityState";
}
else if (typeof document.webkitHidden !== "undefined") {
hidden = "webkitHidden", visibilityChange = "webkitvisibilitychange", visibilityState = "webkitVisibilityState";
}




if (typeof document.addEventListener === "undefined" || typeof hidden === "undefined") {
// not supported
}
else {
document.addEventListener(visibilityChange, function() {
console.log("hidden: " + document[hidden]);
console.log(document[visibilityState]);


switch (document[visibilityState]) {
case "visible":
// visible
break;
case "hidden":
// hidden
break;
}
}, false);
}


if (document[visibilityState] === "visible") {
// visible
}


};
小开

跨浏览器jQuery解决方案! Raw available at GitHub . GitHub

有趣的,易于使用!

下面的插件将通过各种版本的IE, Chrome, Firefox, Safari等的标准测试。并相应地建立您所声明的方法。它还涉及以下问题:

  • onblur | .blur /聚焦事件|。focus“重复的”调用
  • 通过选择替代应用程序，如word，窗口失去焦点
    • <李> < ul >
  • 这往往是不受欢迎的，因为，如果你有一个银行页面打开，并且它的元素失去焦点时事件告诉它屏蔽页面，那么如果你打开计算器，你就再也看不到页面了!
    • 李< / ul > < / >
  • 不触发页面加载

使用方法简单如:向下滚动到“运行片段”

$.winFocus(function(event, isVisible) {
console.log("Combo\t\t", event, isVisible);
});


//  OR Pass False boolean, and it will not trigger on load,
//  Instead, it will first trigger on first blur of current tab_window
$.winFocus(function(event, isVisible) {
console.log("Combo\t\t", event, isVisible);
}, false);


//  OR Establish an object having methods "blur" & "focus", and/or "blurFocus"
//  (yes, you can set all 3, tho blurFocus is the only one with an 'isVisible' param)
$.winFocus({
blur: function(event) {
console.log("Blur\t\t", event);
},
focus: function(event) {
console.log("Focus\t\t", event);
}
});


//  OR First method becoms a "blur", second method becoms "focus"!
$.winFocus(function(event) {
console.log("Blur\t\t", event);
},
function(event) {
console.log("Focus\t\t", event);
});

. 
/*    Begin Plugin    */
;;(function($){$.winFocus||($.extend({winFocus:function(){var a=!0,b=[];$(document).data("winFocus")||$(document).data("winFocus",$.winFocus.init());for(x in arguments)"object"==typeof arguments[x]?(arguments[x].blur&&$.winFocus.methods.blur.push(arguments[x].blur),arguments[x].focus&&$.winFocus.methods.focus.push(arguments[x].focus),arguments[x].blurFocus&&$.winFocus.methods.blurFocus.push(arguments[x].blurFocus),arguments[x].initRun&&(a=arguments[x].initRun)):"function"==typeof arguments[x]?b.push(arguments[x]):
"boolean"==typeof arguments[x]&&(a=arguments[x]);b&&(1==b.length?$.winFocus.methods.blurFocus.push(b[0]):($.winFocus.methods.blur.push(b[0]),$.winFocus.methods.focus.push(b[1])));if(a)$.winFocus.methods.onChange()}}),$.winFocus.init=function(){$.winFocus.props.hidden in document?document.addEventListener("visibilitychange",$.winFocus.methods.onChange):($.winFocus.props.hidden="mozHidden")in document?document.addEventListener("mozvisibilitychange",$.winFocus.methods.onChange):($.winFocus.props.hidden=
"webkitHidden")in document?document.addEventListener("webkitvisibilitychange",$.winFocus.methods.onChange):($.winFocus.props.hidden="msHidden")in document?document.addEventListener("msvisibilitychange",$.winFocus.methods.onChange):($.winFocus.props.hidden="onfocusin")in document?document.onfocusin=document.onfocusout=$.winFocus.methods.onChange:window.onpageshow=window.onpagehide=window.onfocus=window.onblur=$.winFocus.methods.onChange;return $.winFocus},$.winFocus.methods={blurFocus:[],blur:[],focus:[],
exeCB:function(a){$.winFocus.methods.blurFocus&&$.each($.winFocus.methods.blurFocus,function(b,c){this.apply($.winFocus,[a,!a.hidden])});a.hidden&&$.winFocus.methods.blur&&$.each($.winFocus.methods.blur,function(b,c){this.apply($.winFocus,[a])});!a.hidden&&$.winFocus.methods.focus&&$.each($.winFocus.methods.focus,function(b,c){this.apply($.winFocus,[a])})},onChange:function(a){var b={focus:!1,focusin:!1,pageshow:!1,blur:!0,focusout:!0,pagehide:!0};if(a=a||window.event)a.hidden=a.type in b?b[a.type]:
document[$.winFocus.props.hidden],$(window).data("visible",!a.hidden),$.winFocus.methods.exeCB(a);else try{$.winFocus.methods.onChange.call(document,new Event("visibilitychange"))}catch(c){}}},$.winFocus.props={hidden:"hidden"})})(jQuery);
/*    End Plugin      */


// Simple example
$(function() {
$.winFocus(function(event, isVisible) {
$('td tbody').empty();
$.each(event, function(i) {
$('td tbody').append(
$('<tr />').append(
$('<th />', { text: i }),
$('<td />', { text: this.toString() })
)
)
});
if (isVisible)
$("#isVisible").stop().delay(100).fadeOut('fast', function(e) {
$('body').addClass('visible');
$(this).stop().text('TRUE').fadeIn('slow');
});
else {
$('body').removeClass('visible');
$("#isVisible").text('FALSE');
}
});
})
body { background: #AAF; }
table { width: 100%; }
table table { border-collapse: collapse; margin: 0 auto; width: auto; }
tbody > tr > th { text-align: right; }
td { width: 50%; }
th, td { padding: .1em .5em; }
td th, td td { border: 1px solid; }
.visible { background: #FFA; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h3>See Console for Event Object Returned</h3>
<table>
<tr>
<th><p>Is Visible?</p></th>
<td><p id="isVisible">TRUE</p></td>
</tr>
<tr>
<td colspan="2">
<table>
<thead>
<tr>
<th colspan="2">Event Data <span style="font-size: .8em;">{ See Console for More Details }</span></th>
</tr>
</thead>
<tbody></tbody>
</table>
</td>
</tr>
</table>

小开

奇怪的是没有人提到document.hasFocus

if (document.hasFocus()) console.log('Tab is active')

MDN有更多信息

小开

发布这个答案是因为我在接受的答案中发现了一个错误。

这个错误是当你在焦点窗口上打开一个开发人员控制台并单击它的任何地方时，开发人员控制台现在有焦点，此时window.onfocus或window.onblur没有任何影响。

这是我的解，

document.addEventListener("visibilitychange", function() {
if (document.visibilityState === 'visible') {
console.log('has focus');
} else {
console.log('lost focus');
}
});

阅读更多https://developer.mozilla.org/en-US/docs/Web/API/Document/visibilitychange_event

小开

这是10年前的。下面是一个更新的版本:切换标签时暂停/恢复CSS动画

基本上使用Mozillas Javascript https://developer.mozilla.org/en-US/docs/Web/API/Window/focus_event

 function pause() {


//Do something


}


function play() {


//Do something


}
window.addEventListener('blur', pause);
window.addEventListener('focus', play);
小开

一个反应钩版本，基于上面所有这些优秀先生的答案:

import { useEffect, useState } from 'react';


const EVENT_NAME = 'visibilitychange';


export const useTabFocus = () => {
const [hasFocus, setHasFocus] = useState(isVisible());


useEffect(() => {
const onVisibilityChange = () => {
setHasFocus(isVisible());
};


document.addEventListener(EVENT_NAME, onVisibilityChange);


return () => {
document.removeEventListener(EVENT_NAME, onVisibilityChange);
};
}, []);


return hasFocus;
};


const isVisible = () => document.visibilityState === 'visible';

提交答案