如何在javascript中保存对象变量的状态？

Question

这里是我的代码：

var theObj = { 
    localepath:false, 
    settings:false, 
    localeObj:false, 
    callAjax: function(relative_path, callback){ 
     var Ajax = new XMLHttpRequest(); 
     var serialized = false; 
     Ajax.onreadystatechange = function() { 

      //Since what we are calling a local file. we cannot get a 200 OK Status. 
      //So We check only the readystate 
      if(Ajax.readyState==4){ 
       serialized = Ajax.responseText; 
       callback(serialized); 
      } 

     } 

     Ajax.open("GET",relative_path, true); 
     Ajax.send();  
    }, 

    readSettings: function(callback){ 
     var data = this.callAjax('settings.json', function(data){ 
      this.settings = JSON.parse(data); 
      callback(this.settings); 
     }); 
    }, 

    readLocale: function(localepath, callback){ 
     var data = this.callAjax('locale/'+localepath+'.json', function(data){ 
      this.localeObj = JSON.parse(data); 
      callback(); 
     }); 
    }, 

    writeContent: function(id, typeofElement, content){ 
     var currentElement = document.createElement(typeofElement); 
     currentElement.setAttribute('id', id); 
     currentElement.innerHTML = this.l10n(content); 
     document.body.appendChild(currentElement); 
    }, 

    l10n: function(content){ 
     var localeObject = this.localeObj; 
     alert(localeObject); //<< This will alert the cause 
     var arr = content.split(" ").reverse(); //Split by space. and reverse (actually non-reversed) the order 
     var newArr =[]; //Container 
     for (var i = arr.length - 1; i >= 0; i--) { 
      // if the word does not have one-to-one mapping: 
      if(localeObject[arr[i]] == undefined){ 
       if(isNaN(Number(arr[i]))){ 
       //^^ if the word is not a number 
       newArr.push(arr[i]); //do not translate. 
       } else { //if the word is collection of digits 
        var nums = arr[i].split('').reverse(); //Same old split and (non)-reverse 
        var convNums = []; //Same old container 
        for (var j = nums.length - 1; j >= 0; j--) { 
         convNums.push(localeObject[nums[j]]); 
         //iterate and push digits 
        } 
        newArr.push(convNums.join('')); //Make those digits a word! :) 
       } 
      } else { //This means the word has a one-to-one mapping: 
       newArr.push(localeObject[arr[i]]); 
      } 
     } 
     return newArr.join(" "); //Join all with spaces. 
    }, 

    setLocalePath: function(path_to_locale){ 
     this.localepath = path_to_locale; 
    }, 
    getLocaleDefault:function(settings){ 
     return settings.locale[settings.defaultLocale]; 
    } 
}; 

现在，当我这样做：

theObj.readSettings(function(settings){ 
     theObj.readLocale(theObj.getLocaleDefault(settings), function(){ 
      //Start Writing contents here    
      theObj.writeContent('top', 'div', 'looma-f5'); 
      theObj.writeContent('content', 'div','test 132'); 

    }); 
}); 

它告诫假，两次，这意味着该方法theObj.readLocale()没有的内容保存到this.localeObj？为什么会发生？我试图做var newObj = new theObj();哪些不起作用。任何解决方法？

Answer 1

这种类型的问题是由于对this关键字的了解不多所致。这里的主要问题是该方法的localeObj属性从未保存，因为this是从回调中引用的，因此不引用该对象。有一件事可以做到：

..... 
    readLocale: function(localepath, callback){ 
     var that = this; //Now `that` = `this` references the object 
     var data = this.callAjax('locale/'+localepath+'.json', function(data){ 
      that.localeObj = JSON.parse(data); 
      callback(); 
     }); 
    }, 
....