Javascript:根据对象属性将2个对象数组合并为一个新的数组

Question

我在javascript中有两个JSON对象数组，我想从其中创建一个新数组，在属性"Word_No“上映射它们，它们如下所示：

wordInfo (长度4000)：

    [
    {
        "Word_No": "0",
        "Alarm_Bit": "0",
        "Alarm_No": "1",
        "Alarm_Description": "Alarm text 1"
    },
    {
        "Word_No": "0",
        "Alarm_Bit": "1",
        "Alarm_No": "2",
        "Alarm_Description": "Alarm text 2"
    },
    {
        "Word_No": "0",
        "Alarm_Bit": "2",
        "Alarm_No": "3",
        "Alarm_Description": "Alarm text 3"
    }
]

和wordTags (长度250)：

    [
    {
        "Word_No": "0",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15"
    },
    {
        "Word_No": "1",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm16_31"
    },
    {
        "Word_No": "2",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm32_47"
    }
]

我需要成为一个新的数组: Alarmlist (长度4000)：

    [
    {
        "OPC Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15",
        "Alarm_Bit": "0",
        "Alarm_No": "1",
        "Alarm_Description": "Alarm text 1"
    },
    {
        "OPC Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15",
        "Alarm_Bit": "1",
        "Alarm_No": "2",
        "Alarm_Description": "Alarm text 2"
    },
    {
        "OPC Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15",
        "Alarm_Bit": "2",
        "Alarm_No": "3",
        "Alarm_Description": "Alarm text 3"
    }
]

当我尝试使用2 for循环和Word_No属性上的映射构建这个函数时，它会崩溃。

    for (i = 0; i < wordInfo.length; ++i){  //Outer loop  
    for (j = 0; j < wordTags.length; ++j){  //Inner loop
        msg.Info_Word_No = wordInfo[i].Word_No //Woordnr
        msg.Tag_Word_No = wordTags[j].Word_No //Woordnr
        node.send(msg);
    } 
}

当我将i和j限制在例如10时，函数将执行并在调试窗口中显示单词号。

我的想法是绘制这样的地图：

if(wordInfo[i].Word_No == wordTags[i].Word_No){
            var alarmTagInfo;
            alarmTagInfo.Alarm_No=wordInfo[i].Alarm_No;
            alarmTagInfo.OPC_Tag = wordTags[i].OPC_Tag;
            alarmTagInfo.Alarm_Bit = wordInfo[i].Alarm_Bit;
            msg.payload = alarmTagInfo;
            alarmlist.push(alarmTagInfo);
        }

但是由于数组太大，Node应用程序就会崩溃。我不知道怎样才能有效地处理这件事？

Answer 1

我建议首先使用OPC_Tag上的Array.reduce()为wordTags创建一个查找对象--这将提高性能，避免为wordInfo上的循环的每一次迭代执行.find()。

然后，我们将使用Array.map() on wordInfo来创建最终结果：

​

let wordInfo = [ { "Word_No": "0", "Alarm_Bit": "0", "Alarm_No": "1", "Alarm_Description": "Alarm text 1" }, { "Word_No": "0", "Alarm_Bit": "1", "Alarm_No": "2", "Alarm_Description": "Alarm text 2" }, { "Word_No": "0", "Alarm_Bit": "2", "Alarm_No": "3", "Alarm_Description": "Alarm text 3" } ]
let wordTags = [ { "Word_No": "0", "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15" }, { "Word_No": "1", "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm16_31" }, { "Word_No": "2", "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm32_47" } ] 

// Create a lookup, mapping Word_No to OPC_Tag
let wordTagsLookup = wordTags.reduce((acc, { Word_No, OPC_Tag }) => { 
    acc[Word_No] = OPC_Tag;
    return acc;
}, {})

let result = wordInfo.map(({ Word_No, Alarm_Bit, Alarm_No, Alarm_Description}) => { 
    return { Alarm_Bit, Alarm_No, Alarm_Description, OPC_Tag: wordTagsLookup[Word_No] };
})

console.log('Result:', result)

.as-console-wrapper { max-height: 100% !important; }

​

Answer 2

我建议为第二个数组创建一个Map，该数组由Word_No键决定。然后将该数组映射到使用该Map进行转换的对象。随着对象的破坏，这可能会变得非常优雅：

​

// Sample input data
const wordInfo = [{"Word_No": "0","Alarm_Bit": "0","Alarm_No": "1","Alarm_Description": "Alarm text 1"},{"Word_No": "0","Alarm_Bit": "1","Alarm_No": "2","Alarm_Description": "Alarm text 2"},{"Word_No": "0","Alarm_Bit": "2","Alarm_No": "3","Alarm_Description": "Alarm text 3"}];
const wordTags = [{"Word_No": "0","OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15"},{"Word_No": "1","OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm16_31"},{"Word_No": "2","OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm32_47"}];

// Create map keyed by Word_No:
const map = new Map(wordTags.map(({Word_No, OPC_Tag}) => ([Word_No, OPC_Tag])));
// Translate the source data to the target data
const alarmList = wordInfo .map(({Word_No, ...rest}) => 
    ({OPC_Tag: map.get(Word_No), ...rest})
); 
console.log(alarmList);

​

Answer 3

对我来说，您可以这样做，只需使用.map()和.filter()方法：

const wordInfo = [
  {
      "Word_No": "0",
      "Alarm_Bit": "0",
      "Alarm_No": "1",
      "Alarm_Description": "Alarm text 1"
  },
  {
      "Word_No": "0",
      "Alarm_Bit": "1",
      "Alarm_No": "2",
      "Alarm_Description": "Alarm text 2"
  },
  {
      "Word_No": "0",
      "Alarm_Bit": "2",
      "Alarm_No": "3",
      "Alarm_Description": "Alarm text 3"
  },
];

const wordTags = [
    {
        "Word_No": "0",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm0_15"
    },
    {
        "Word_No": "1",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm16_31"
    },
    {
        "Word_No": "2",
        "OPC_Tag": "HH.Application.TmpHmi_Var.TmpHmiC7.Alarm32_47"
    }
];

const data = wordInfo.map((wordInfoItem) => {
  const wordTag = wordTags
    .filter((wordTagItem) => (wordInfoItem["Word_No"] === wordTagItem["Word_No"]))[0];
  
  const newArray = {
    ...wordTag,
    ...wordInfoItem,
  };

  delete newArray['Word_No'];
  return newArray;
});

console.log(data);