Javascript 在对象回调中设置对象属性

Question

我正在尝试在另一个对象的回调方法中设置一个对象(摘要)

returnObj.beforeLoadComplete = function (records) {
    var someObj = {
        total: {
            label: 'Items',
            value: '15'
        },
        additional: [{
            label: 'Item1 Total',
            value: '25000'
        }]
    };

    returnObj.summary = summaryObj;
    // some other code which finally returns an object
}

上面的代码不起作用(即 summary 没有在 returnObj 上设置)

但是，如果我在回调方法之外有相同的代码，它会像下面的代码片段一样工作:

var someObj = {
    total: {
        label: 'Items',
        value: '15'
    },
    additional: [{
        label: 'Item1 Total',
        value: '25000'
    }]
};

returnObj.summary = summaryObj;
returnObj.beforeLoadComplete = function (records) {
    // some other code which finally returns an object
}

不知道为什么会这样。

Answer 1

您必须使用 this 访问您的对象声明，我还纠正了一些错字:

var returnObj = {};
returnObj.beforeLoadComplete = function (records) {
    var someObj = {
        total: {
            label: 'Items',
            value: '15'
        },
        additional: [{
            label: 'Item1 Total',
            value: '25000'
        }]
    };
    // Access object with this
    this.summary = someObj;
    // some other code which finally returns an object
}
returnObj.beforeLoadComplete('records');
console.log(returnObj.summary);

更新:添加代码片段以验证returnObj 是否可以通过回调处理程序中的此访问。

var returnObj = {};
returnObj.beforeLoadComplete = function () {
  var someObj = {
    total: {
      label: "Items",
      value: "15"
    },
    additional: [{
      label: 'Item1 Total',
      value: '25000'
    }]
  };
  this.summary = someObj;
  // some other code which finally returns an object
}
//returnObj.beforeLoadComplete();

function verifyObjectUpdated(){
   alert(returnObj.summary);
}

<select onChange="returnObj.beforeLoadComplete()">
  <option>Trigger onChange to add summary to your returnObj</option>
  <option>Trigger onChange to add summary to your returnObj</option>
</select>

<select onChange="verifyObjectUpdated()">
  <option>Trigger onChange to alert summary of returnObj ( do it after adding summary)</option>
  <option>Trigger onChange to alert summary of returnObj ( do it after adding summary)</option>
</select>