web游覽器的標簽頁仿 ios mac 蘋果的墓碑機制 (js代碼)

背景：

本來項目開發系統防掛機功能，在其餘游覽器中均可以使用。但是呢在蘋果的safair游覽器中會出現幾率失效，最後經過排查發現是蘋果的墓碑機制導致。即：此標簽頁活躍，其他標簽頁假死。然後就導致防掛機失效了。

原理：

假如當前游覽器中有3個標簽頁分別是A,B,C，每個標簽頁都有倒計時。正常情況下，每個標簽頁都會倒計時。但是蘋果游覽器只會有一個標簽頁A正常倒計時，其餘的B，C 倒計時不生效。

所以就需要仿墓碑機制進行開發。原理如下：

A標簽頁打開時，B和C標簽頁不活躍；

當打開其他標簽頁，ABC處於後臺時候，最近操作的一個標簽頁處於活躍；

核心邏輯代碼：

    //分鐘數
         var min;
        var timeLeft; 
        var timer=null; 
        var IsnewRequest = false;
        var StayTimer = null;
        function resetTimer() {
            backInit();
        }

        function uuid(len, radix) {
            var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');
            var uuid = [], i;
            radix = radix || chars.length;

            if (len) {
                // Compact form
                for (i = 0; i < len; i++) uuid[i] = chars[0 | Math.random()*radix];
            } else {
                // rfc4122, version 4 form
                var r;

                // rfc4122 requires these characters
                uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-';
                uuid[14] = '4';

                // Fill in random data.  At i==19 set the high bits of clock sequence as
                // per rfc4122, sec. 4.1.5
                for (i = 0; i < 36; i++) {
                if (!uuid[i]) {
                    r = 0 | Math.random()*16;
                    uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];
                }
                }
            }

            return uuid.join('');
        }


        function GetBigTime() {

            //判斷：如果有其他頁面打開，則賦值最大倒計時值，如果< 10 退出
            //1,獲取所有的time
            //2，取最大的時間
            //3，如果最大的時間<10 則不管；
            var countDownKeyList= [];    
            var localStorageKeys = Object.keys(localStorage)
            for (var i=0;i<localStorageKeys.length;i++) {        
                var item = localStorageKeys[i];
                if(item.indexOf("CountDown")!=-1)
                {
                countDownKeyList.push(item);
                }                  
            }

            var countDownValueList= [];    
            for(var i= 0; i<countDownKeyList.length;i++)
            {
                var value = localStorage.getItem(countDownKeyList[i]);
                countDownValueList.push(value);
            }

            //驗證最大時間
            var bigTime = countDownValueList.sort().reverse()[0];
            //if(Number(bigTime)>=3)
            if(Number(bigTime)>=3 && Number(bigTime) != 19999999)            
            {
                //取運行中的倒計時最大值；      
                window.localStorage.setItem(window.CountDown,bigTime); 
                return false;
            }
            else
            {
                window.localStorage.removeItem(window.CountDown); 
                return true;
            }

        }

        function  ShowCountDown (second){
            const s = second % 60;
            const m = Math.floor(second / 60);
            return `${`00${m}`.slice(-2)} : ${`00${s}`.slice(-2)}`;
        };  


        function reSetTimeoutInit()
        {
            window.localStorage.setItem("checkClose","1");
            setTimeout(function(){
            //1秒後執行刷新          
            window.localStorage.removeItem('checkClose');
            }, 1000); //單位是毫秒   
            setTimeoutInit();
        }

        var IsResetTime = false;
        function setTimeoutInit() {
             
            this.IsnewRequest = true;
            //預設無操作時間為15分鐘
            min = 15;
            let value = window.localStorage.getItem("InvalidTime");    
            //如果取不到session值 則預設15分鐘
            if(value!=null && value!=undefined)
            {
                min =  Number(value);                 
            }            

  

            //清理之前的倒計時
            clearInterval(StayTimer);


            //沒有唯一標識，則生成
            if(window.CountDown==''||window.CountDown==undefined)
            {      
                window.CountDown = "CountDown"+this.uuid(8,2);                
            }

            //設置初始倒計時
            var MainTime = min * 60;            
            window.localStorage.setItem(window.CountDown,MainTime);     

            StayTimer = setInterval(()=>{

                var nowTime = window.localStorage.getItem(window.CountDown);
                if(nowTime==null||nowTime=="")
                {
                    clearInterval(StayTimer);
                    return;
                }
                //獲取存儲倒計時
                timeLeft = Number(nowTime);            

                var localStorageKeys = Object.keys(localStorage)
                var labelList =  localStorageKeys.filter(x=> x.indexOf("CountDown")!=-1 );      
                var activeCount = 0;
                for(var i= 0; i<labelList.length;i++)
                {
                    var value = localStorage.getItem(labelList[i]);
                    var nValue =  Number.parseInt(value);
                    if(nValue!=19999999)
                    {
                    activeCount++;
                    }        
                }      

                var localStorageKeys = Object.keys(localStorage)
                var labelList =  localStorageKeys.filter(x=> x.indexOf("CountDown")!=-1 );      
                var activeCount = 0;
                for(var i= 0; i<labelList.length;i++)
                {
                    var value = localStorage.getItem(labelList[i]);
                    var nValue =  Number.parseInt(value);
                    if(nValue!=19999999)
                    {
                    activeCount++;
                    }        
                }
                //如果沒有一個活躍，則重新讀取
                if(activeCount==0)
                {
                    this.IsnewRequest = true;
                }

                if(this.IsnewRequest==true)
                {
                    this.IsnewRequest = false;
                    for(var i= 0; i<labelList.length;i++)
                    {
                    if(labelList[i]!=window.CountDown)
                    {
                        var value = localStorage.getItem(labelList[i])
                        localStorage.setItem(labelList[i],"19999999");
                    }
                    else
                    {
                        timeLeft = MainTime;//設置的預設值           
                        localStorage.setItem(labelList[i],MainTime);
                    }
                    }      
                }      



                if (document.hidden) {
                    //首先重置時間
                    //賦值其餘的為-999
                    if(timeLeft==19999999)
                    {
                    IsResetTime = true
                    const show = ShowCountDown(timeLeft);//恢復倒計時 並且重置時間；
                    console.log("[時停],倒計時："+timeLeft);                                                           
                    }
                    else
                    {          
                    if(IsResetTime)
                    {
                        timeLeft = MainTime;//設置的預設值           
                        IsResetTime = false;
                    }                       
                    const show = ShowCountDown(timeLeft--);//恢復倒計時 並且重置時間；
                    console.log("[獨苗],倒計時："+timeLeft);                                                           
                    }
                } else {            
                    //首先重置時間
                    //賦值其餘的為-999
                    if(timeLeft==19999999)
                    {
                    IsResetTime = true
                    const show = ShowCountDown(timeLeft);//恢復倒計時 並且重置時間；
                    console.log("[時停],倒計時："+timeLeft);                                                           
                    }
                    else
                    {          
                    if(IsResetTime)
                    {
                        timeLeft = MainTime;//設置的預設值           
                        IsResetTime = false;
                    }                       
                    const show = ShowCountDown(timeLeft--);//恢復倒計時 並且重置時間；
                    console.log("[獨苗],倒計時："+timeLeft);                                                           
                    }
                }      


                var checkShow = window.localStorage.getItem('checkShow');
                var blCheckShow =Number(checkShow);
                if(blCheckShow==1)
                {
                    timeLeft = -1;
                    setTimeout(function(){
                    //1秒後執行刷新          
                    window.localStorage.removeItem('checkShow');
                    }, 1000); //單位是毫秒                    
                }
                
                //const show = ShowCountDown(timeLeft--);
                //設置倒計時
                window.localStorage.setItem(window.CountDown,timeLeft);     
                if (timeLeft < 0) 
                {
                    //#endregion                    
                    window.localStorage.setItem('checkShow',"1");
                    var IsResetTime = false;    
                    var blresult = this.GetBigTime();
                    if(blresult==true)
                    {
                        //清理定時 
                        clearInterval(StayTimer);
                        //業務操作：
                        document.getElementsByClassName("fullScreenDiv")[0].style.display = "block";
                        document.getElementsByClassName("promptDiv")[0].style.display = "block";
                        startCountDown($("#spanCountDown").text()); 

                    }


                }                    

            },1000);



            //countTime();

            


            var vdoc = document.getElementById("ScormIframe").contentDocument;

            if (vdoc != null) {
                vdoc.addEventListener("mousemove", resetTimer, false);
                vdoc.addEventListener("mousedown", resetTimer, false);
                vdoc.addEventListener("keypress", resetTimer, false);
                vdoc.addEventListener("DOMMouseScroll", resetTimer, false);
                vdoc.addEventListener("mousewheel", resetTimer, false);
                vdoc.addEventListener("touchmove", resetTimer, false);
                vdoc.addEventListener("MSPointerMove", resetTimer, false);
            }
            else{  
            }

            if (language == "zh-CN") {
                        $("#msgInfo").html("由於長時間未操作，課件將在倒計時結束後自動關閉，系統會保存您的學習記錄。");
                        $("#msgTimeout").html("如果您想繼續學習，請關閉此視窗。");
                    }
                    else {
                        $("#msgInfo").html("Since there is no operation for a period of time, the courseware will be closed automatically at the end of the countdown and the learning record will be saved.");
                        $("#msgTimeout").html("If you want to continue learning, just close this window.");
                    }
        } 



        function countTime() {
                if (timeLeft == 0) {
                    document.getElementsByClassName("fullScreenDiv")[0].style.display = "block";
                    document.getElementsByClassName("promptDiv")[0].style.display = "block";
                    startCountDown($("#spanCountDown").text()); 
                }

                var startMinutes = parseInt(timeLeft / (60 * 1000), 10);
                var startSec = parseInt((timeLeft - startMinutes * 60 * 1000) / 1000)
                timeLeft = timeLeft - 1000;
                setTimeout('countTime()', 1000);
                //console.log(timeLeft);
            }

            function startCountDown(html){
                clearInterval(this.CountDownTimer);
                        this.CountDownTimer = setInterval(() => {

                            var checkClose = window.localStorage.getItem('checkClose');
                            var blCheckClose =Number(checkClose);
                            if(blCheckClose==1)                            
                            {                                
                                // $("#spanCountDown").text(60);
                                // clearInterval(this.CountDownTimer);
                                document.getElementsByClassName("fullScreenDiv")[0].style.display = "none";
                                document.getElementsByClassName("promptDiv")[0].style.display = "none";                                
                                setTimeoutInit();
                                setTimeout(function(){
                                //1秒後執行刷新
                                window.localStorage.removeItem('checkClose');
                                }, 1000); //單位是毫秒     
                            }
                            else
                            {
                                html = parseInt(html) - 1; 
                                if (parseInt(html) <= 0) {
                                    closeme();
                                }
                                $("#spanCountDown").text(html);
                            }                                                    
                            ////console.log($("#spanCountDown").text());
                        }, 1000);
            }
        function closeme() {
            var browserName = navigator.appName;
            if (browserName == "Netscape") {
                window.open('', '_parent', '');
                window.close();
            } else if (browserName == "Microsoft Internet Explorer") {
                window.opener = "whocares";
                window.close();
            }
        }


        function backInit() {

                reSetTimeoutInit();                

                // min = 15;
                // timeLeft = min * 60 * 1000;
                $("#spanCountDown").text(60);
                clearInterval(this.CountDownTimer);
                document.getElementsByClassName("fullScreenDiv")[0].style.display = "none";
                document.getElementsByClassName("promptDiv")[0].style.display = "none";
            }

結語：

其實就是按照墓碑機制進行仿照開發，此文章進行記錄以後可以在其他平臺進行此機制的開發；