Javascript Array 使用鍵值條件對唯一對象進行排序

Question

我有一個數組

"datawithisNew": [
        {
            "exam_name": "MPSC",
            "isNew": false
        },
        
        {
            "exam_name": "MPSC",
            "isNew": true
        },
        {
            "exam_name": "UPSC",
            "isNew": false
        },
      
        {
            "exam_name": "RAILWAY",
            "isNew": false
        },
        {
            "exam_name": "RAILWAY",
            "isNew": false
        }]

我想獲得獨特的結果exam_name這樣的對象，導致陣列保存唯一exam_name值也如果exam_name有ATLEAST 1個isNew鍵為真，將產生的對象應該具有與物業isNew true ，如果不是false 。 預期結果——

"datawithisNew": [
        {
            "exam_name": "MPSC",
            "isNew": true
        },

        {
            "exam_name": "UPSC",
            "isNew": false
        },
        {
            "exam_name": "RAILWAY",
            "isNew": false
        }]

我使用的代碼是-

 var helper1 = {};
    var result2 = data12.reduce(function(r, o) {
    var key = o.exam_name ;
    
    if(!helper1[key]) {
      helper1[key] = Object.assign({}, o); // create a copy of o
      r.push(helper1[key]);
    } else {
      helper1[key].exam_name_rating += o.exam_name_rating;
    }
    return r;
  }, []);

但是，這只是返回唯一的exam_name對象我還需要isNew如果發生ATLEAST其關鍵true ATLEAST一次的exam_name它應該有isNew:true為真或者isNew:false

Answer 1

使用 JS Array.filter過濾掉重復項

 const datawithisNew = [{ "exam_name": "MPSC", "isNew": false }, { "exam_name": "MPSC", "isNew": true }, { "exam_name": "UPSC", "isNew": false }, { "exam_name": "RAILWAY", "isNew": false }, { "exam_name": "RAILWAY", "isNew": false } ]; const uniqueItems = datawithisNew.filter((exam, index, self) => { return self.findIndex(e => exam.exam_name === e.exam_name) === index }).map(exam => { if (!exam.isNew && datawithisNew.find(e => e.exam_name === exam.exam_name && e.isNew)) { exam.isNew = true; } return exam; }); console.log(uniqueItems);

Answer 2

使用您的 datawithisNew 作為參數調用下面的函數

     function getUniqueExams(data){
let finalObjMap = { };
for(var i=0;i<data.length;i++){
let currentObj = data[i];
if(finalObjMap[currentObj["exam_name"]])
{
if(!finalObjMap[currentObj["isNew"]] && currentObj["isNew"])
    finalObjMap[currentObj["exam_name"]]["isNew"]=true;
}
else
{
    finalObjMap[currentObj["exam_name"]]={"isNew":currentObj["isNew"]};
}

}
let finalData=[];
Object.keys(finalObjMap).forEach((key)=>{
let tempExamObj  = { "exam_name": key , "isNew": finalObjMap[key]["isNew"]};
finalData.push(tempExamObj);

});
return finalData;
};

    var datawithisNew=[
            {
                "exam_name": "MPSC",
                "isNew": false
            },
            
            {
                "exam_name": "MPSC",
                "isNew": true
            },
            {
                "exam_name": "UPSC",
                "isNew": false
            },
          
            {
                "exam_name": "RAILWAY",
                "isNew": false
            },
            {
                "exam_name": "RAILWAY",
                "isNew": false
            }];
    console.log(getUniqueExams(datawithisNew));

Answer 3

您離實際解決方案不遠，添加以下行可以解決您的問題：

helper1[key].isNew ||= o.isNew;

如果當前值為假， ||=會將變量或屬性分配給一個值。

如果您不能使用邏輯 OR 賦值( ||= ) 運算符，因為它是一個相當新的賦值運算符，您可以使用：

if (!helper1[key].isNew) helper1[key].isNew = o.isNew;

 const data12 = [ { "exam_name": "MPSC", "isNew": false }, { "exam_name": "MPSC", "isNew": true }, { "exam_name": "UPSC", "isNew": false }, { "exam_name": "RAILWAY", "isNew": false }, { "exam_name": "RAILWAY", "isNew": false }, ]; var helper1 = {}; var result2 = data12.reduce(function(r, o) { var key = o.exam_name ; if(!helper1[key]) { helper1[key] = Object.assign({}, o); // create a copy of o r.push(helper1[key]); } else { helper1[key].exam_name_rating += o.exam_name_rating; helper1[key].isNew ||= o.isNew; // <- added this line } return r; }, []); console.log(result2);

由於示例數據不包含exam_name_rating屬性，它將丟失，或者結果設置為NaN 。 我假設此屬性在您自己的數據中可用。