javascript - 在 Javascript 中操作对象数组

标签 javascript arrays object

我不太确定如何在这篇文章的标题中阐明我想要做什么，所以如果标题具有误导性或过于含糊，请原谅我。

我有一个通过 oData 调用创建的对象数组(这是在 SAPUI5 应用程序中)。实际对象具有三个以上的键/值对，但我将它们删除以保持此示例简单。 

[{
  "note_type_description": "General",
  "note_date": "/Date(872850505000)/",
  "note_text": "THIS IS A SUBSIDUARY OF THAT."
}, 
{
  "note_type_description": "General",
  "note_date": "/Date(873072000000)/",
  "note_text": "Say What Now?"
}, 
{
  "note_type_description": "General",
  "note_date": "/Date(891388800000)/",
  "note_text": "Say Who Now?"
},
{
  "note_type_description": "General",
  "note_date": "/Date(891993600000)/",
  "note_text": "Say When Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(909014400000)/",
  "note_text": "Say How Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(906422400000)/",
  "note_text": "Say Valentine Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(1485907200000)/",
  "note_text": "The latest interaction."
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1477958400000)/",
  "note_text": "Some information about Person"
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1483228800000)/",
  "note_text": "Are they private or public?"
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1485907200000)/",
  "note_text": "Hope this is enough information!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1485993600000)/",
  "note_text": "Good!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1487116800000)/",
  "note_text": "Better!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1488412800000)/",
  "note_text": "Best!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1490918400000)/",
  "note_text": "Superb!"
}]

我想迭代对象，并创建一个新的对象数组，其中包含最近条目 (note_date) 的每种类型 (note_type_description) 中的两个，以便我可以在 UI 中呈现它。

我对 JS 有点陌生，所以我主要不清楚我将使用什么数组方法来完成此任务。我认为这将从 Array.map() 开始并从那里开始。任何援助将不胜感激!我将继续努力并发布我在此过程中的任何更新!

** 更新 **

我使用了 @Titus 的示例，这是经过一些修改后的样子(从箭头函数切换到常规函数):

var oArr = [{
  "note_type_description": "General",
  "note_date": "/Date(872850505000)/",
  "note_text": "THIS IS A SUBSIDUARY OF THAT."
}, {
  "note_type_description": "General",
  "note_date": "/Date(873072000000)/",
  "note_text": "Say What Now?"
}, {
  "note_type_description": "General",
  "note_date": "/Date(891388800000)/",
  "note_text": "Say Who Now?"
}, {
  "note_type_description": "General",
  "note_date": "/Date(891993600000)/",
  "note_text": "Say When Now?"
}, {
  "note_type_description": "Interaction",
  "note_date": "/Date(909014400000)/",
  "note_text": "Say How Now?"
}, {
  "note_type_description": "Interaction",
  "note_date": "/Date(906422400000)/",
  "note_text": "Say Valentine Now?"
}, {
  "note_type_description": "Interaction",
  "note_date": "/Date(1485907200000)/",
  "note_text": "The latest interaction."
}, {
  "note_type_description": "Company Information",
  "note_date": "/Date(1477958400000)/",
  "note_text": "Some information about Person"
}, {
  "note_type_description": "Company Information",
  "note_date": "/Date(1483228800000)/",
  "note_text": "Are they private or public?"
}, {
  "note_type_description": "Company Information",
  "note_date": "/Date(1485907200000)/",
  "note_text": "Hope this is enough information!"
}, {
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1485993600000)/",
  "note_text": "Good!"
}, {
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1487116800000)/",
  "note_text": "Better!"
}, {
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1488412800000)/",
  "note_text": "Best!"
}, {
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1490918400000)/",
  "note_text": "Superb!"
}];

var sortedArr = oArr.sort(function(a, b) {
  b.note_date.match(/\d+/)[0] - a.note_date.match(/\d+/)[0]
});
var toRender = [];

sortedArr.forEach(function(v) {
  if (toRender.filter(function(vv) {
      return v.note_type_description == vv.note_type_description
    }).length < 2) {
    toRender.push(v);
  }
});

toRender.forEach(function(oKey) {
  console.log(oKey.note_type_description + " | " + oKey.note_text);
});

***** 更新#2 *****

为了完成这个并提供上下文，我最终得到的是:

    _setNotes: function(oResponse) {
        if (typeof oResponse.results !== "undefined") {
            var aAllNotes = oResponse.results;
            var aTruncNotes = [];

            var sortedNotes = aAllNotes.sort(function(a, b) {
                a = new Date(a.note_date);
                b = new Date(b.note_date);
                return a>b ? -1 : a<b ? 1 : 0;
            });

            sortedNotes.forEach(function(v) {
                if (aTruncNotes.filter(function(vv) {
                        return v.note_type_description === vv.note_type_description;
                    }).length < 2) {
                    aTruncNotes.push(v);
                }
            });
        }
        this.getView().getModel("view").setProperty("/allNotes", aAllNotes);
        this.getView().getModel("view").setProperty("/truncNotes", aTruncNotes);
    }

现在我可以在 UI5 XML View 中调用“truncNotes”对象，它会按如下方式返回:

enter image description here

最佳答案

实现此目的的一种方法是首先按 note_date 对数组进行排序，然后创建一个新数组并仅向其中添加 2 个具有相同 note_type_description 值的对象.

这是一个例子:

var arr = [{
  "note_type_description": "General",
  "note_date": "/Date(872850505000)/",
  "note_text": "THIS IS A SUBSIDUARY OF THAT."
}, 
{
  "note_type_description": "General",
  "note_date": "/Date(873072000000)/",
  "note_text": "Say What Now?"
}, 
{
  "note_type_description": "General",
  "note_date": "/Date(891388800000)/",
  "note_text": "Say Who Now?"
},
{
  "note_type_description": "General",
  "note_date": "/Date(891993600000)/",
  "note_text": "Say When Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(909014400000)/",
  "note_text": "Say How Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(906422400000)/",
  "note_text": "Say Valentine Now?"
},
{
  "note_type_description": "Interaction",
  "note_date": "/Date(1485907200000)/",
  "note_text": "The latest interaction."
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1477958400000)/",
  "note_text": "Some information about Person"
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1483228800000)/",
  "note_text": "Are they private or public?"
},
{
  "note_type_description": "Company Information",
  "note_date": "/Date(1485907200000)/",
  "note_text": "Hope this is enough information!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1485993600000)/",
  "note_text": "Good!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1487116800000)/",
  "note_text": "Better!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1488412800000)/",
  "note_text": "Best!"
},
{
  "note_type_description": "Relationship Strategy",
  "note_date": "/Date(1490918400000)/",
  "note_text": "Superb!"
}];

var sortedArr = arr.sort((a, b) => b.note_date.match(/\d+/)[0] - a.note_date.match(/\d+/)[0]);
var toRender = [];

sortedArr.forEach(v => {
    if(toRender.filter(vv => v.note_type_description == vv.note_type_description).length < 2){
         toRender.push(v);
    }
});

console.log(toRender);

这不是最有效的方法，但它将向您介绍 JavaScript 数组函数，例如 sort、filter 和 forEach

关于javascript - 在 Javascript 中操作对象数组，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42583420/

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