js如何判斷當前頁面是否處於激活狀態

轉載：https://blog.csdn.net/yihanzhi/article/details/89965589

方式1：監聽事件visibilitychange
具體實現方式如下：

var hiddenProperty = 'hidden' in document ? 'hidden' :    
    'webkitHidden' in document ? 'webkitHidden' :    
    'mozHidden' in document ? 'mozHidden' :  null;
var visibilityChangeEvent = hiddenProperty.replace(/hidden/i, 'visibilitychange');
var onVisibilityChange = function(){
    if (!document[hiddenProperty]) {    
        alert("未激活狀態！");
    }else{
        alert("激活狀態！")
    }
}
document.addEventListener(visibilityChangeEvent, onVisibilityChange);

方式2：監聽事件blur和focus

window.onblur = function(e){
    console.log("未激活狀態！")
}
window.onfocus = function(e){
    console.log("激活狀態！")
}