JavaScript有没有一种方法可以检测浏览器窗口当前是否未激活？

自从最初编写此答案以来，新的规范已达到推荐状态。现在，页面可见性API使我们能够更准确地检测页面何时向用户隐藏。

document.addEventListener("visibilitychange", onchange);

当前的浏览器支持：

• hrome 13+
• Internet Explorer 10+
• Firefox 10+
• Opera 12.10+ [read notes]

以下代码会退回到不兼容浏览器中不太可靠的模糊/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"});})();

onfocusin

onfocusout

onfocus

onblur

onpageshow

onpagehide