Question

我构建了一个应用程序，然后我使用PhoneGap Build构建。目的是运行代码（在加载应用程序时每天var Quotes启动一次）。

在调试它为什么不起作用时，我注意到在控制台中我收到了我的消息＆＃34;本地存储没有工作＆＃34;。这意味着我应该确保可以读取本地存储的初始localstorage.getItem返回null。所以我的代码永远不会被执行。

我做错了什么？

function onDeviceReady() { //Do something when the app on device is loaded

var localVal = localStorage.getItem('DateOpened'); 

if(localVal  == null){ 

   console.log("LocalStorage did not work...")}

else
{
  var tempd = new Date(); //Get today's date
  var str = tempd.getDay() + tempd.getMonth() + tempd.getFullYear();
  if(localVal.localeCompare(str) == -1) 
              { 
                            var Quotes = [];
                            var ID = [];
                            var Tag = [];
                            var seen = [];

    localStorage.setItem('DateOpened',str);
    console.log("The App Ran, you can get a new fat tomorrow");
    console.log("Todays date:" + str);
  }
 }
}

Answer 1

最初，本地存储中没有DateOpened项，因此您的代码将遵循“无效”分支，因为getItem会返回null存在。该分支从未在DateOpened中设置任何内容，因此......您将始终遵循该分支。

如果设备具有本地存储空间，则修复不会跳过代码设置DateOpened。

还存在一个无关的问题：您的var str = tempd.getDay() + tempd.getMonth() + tempd.getFullYear() 不会产生一个字符串，它会产生一个由将这些值加在一起形成的数字，因为它们是所有数字。您以后的localeCompare将失败，因为它不是字符串。您还有错误顺序的字段，以进行有意义的文本比较 - 您需要先按年份，然后按月，然后按一天。

这是一个最小的修复，请参阅注释：

function onDeviceReady() {

    var tempd = new Date();
    // Note that by adding strings in there, we end up with a string instead of adding.
    // Note the order: Year first, then month, then day.
    // Also, since we display it, we put separators in and add 1 to month (since Jan = 0).
    var str = tempd.getFullYear() + "-" + (tempd.getMonth() + 1) + "-" + tempd.getDay();
    var localVal = localStorage.getItem('DateOpened');

    // If we have no stored value, or it's more than a day old by your definition,
    // do your stuff and store the new date
    if (localVal == null || localVal.localeCompare(str) < 0) {
        var Quotes = [];
        var ID = [];
        var Tag = [];
        var seen = [];

        localStorage.setItem('DateOpened', str);
        console.log("The App Ran, you can get a new fat tomorrow");
        console.log("Todays date:" + str);
    }
}

Answer 2

我认为这对你来说很有帮助。

function onDeviceReady() { //Do something when the app on device is loaded

var localVal = localStorage.getItem('DateOpened'); 

if (typeof(DateOpened) == "undefined") 

   console.log("LocalStorage did not work...")}

else
{
  var tempd = new Date(); //Get today's date
  var str = tempd.getDay() + tempd.getMonth() + tempd.getFullYear();
  var allRecords=JSON.parse(localStorage.getItem("DateOpened"));     
  if(allRecords == -1) 
              { 
                            var Quotes = [];
                            var ID = [];
                            var Tag = [];
                            var seen = [];

    localStorage.setItem('DateOpened',str);
    console.log("The App Ran, you can get a new fat tomorrow");
    console.log("Todays date:" + str);
  }
 }
}

本地存储未按预期工作

2 个答案: