如何使用 JavaScript 合并不同的 JSON 对象？

Question

How to merge these JSON objects using JavaScript?

If one key is missing then put null in the place of the value

Convert from:

[{"dateData": "2019-04-08", "geriatricDepressionScaleTotalScoreData": "5"}, 
{"dateData": "2019-04-09", "geriatricDepressionScaleTotalScoreData": "2"}]

[{"dateData": "2019-04-08", "digitSpanTotalScoreData": "10"},
{"dateData": "2019-04-09", "digitSpanTotalScoreData": "12"}]

[{"dateData": "2019-04-09", "immediateRecallStoryAData": "4", 
"delayedRecallStoryAData": "6"}]

[{"dateData": "2019-04-08", "phonologicalTotalData": "30"},
{"dateData": "2019-04-09", "phonologicalTotalData": "4"}]

Convert To:

[{"dateData": "2019-04-08", "geriatricDepressionScaleTotalScoreData": "5",
"digitSpanTotalScoreData": "10", "immediateRecallStoryAData": null,
"delayedRecallStoryAData": null, "phonologicalTotalData": "30"}, 
{"dateData": "2019-04-09", "geriatricDepressionScaleTotalScoreData": "2",
"digitSpanTotalScoreData": "12", "immediateRecallStoryAData": 4,
"delayedRecallStoryAData": 6, "phonologicalTotalData": "4"}]

Answer 1

You can do it using spread operator like

var myArr = [{ "dateData": "2019-04-08", "geriatricDepressionScaleTotalScoreData": "5" }, { "dateData": "2019-04-09", "geriatricDepressionScaleTotalScoreData": "2" }];
    myArr.push(...[{ "dateData": "2019-04-08", "digitSpanTotalScoreData": "10" }, { "dateData": "2019-04-09", "digitSpanTotalScoreData": "12" }]);
    myArr.push(...[{ "dateData": "2019-04-09", "immediateRecallStoryAData": "4", "delayedRecallStoryAData": "6" }]);
    myArr.push(...[{ "dateData": "2019-04-08", "phonologicalTotalData": "30" }, { "dateData": "2019-04-09", "phonologicalTotalData": "4" }]);

    var final = JSON.stringify(myArr);
    console.log(final);

Answer 2

You can use Array .map() function to reformat the existing array of objects to a new array with newly reformatted objects.

const arr = [{"dateData": "2019-04-08", "geriatricDepressionScaleTotalScoreData": "5"},
             {"dateData": "2019-04-09", "geriatricDepressionScaleTotalScoreData": "2"}];

const result = arr.map((el) => {
    const obj = {};
   obj['dateData'] = el.hasOwnProperty('dateData')?el['dateData'] :null;
   obj['geriatricDepressionScaleTotalScoreData'] = el.hasOwnProperty('geriatricDepressionScaleTotalScoreData')?el['geriatricDepressionScaleTotalScoreData'] :null;
   obj['digitSpanTotalScoreData'] = el.hasOwnProperty('digitSpanTotalScoreData')?el['digitSpanTotalScoreData'] :null;
   obj['immediateRecallStoryAData'] = el.hasOwnProperty('immediateRecallStoryAData')?el['immediateRecallStoryAData'] :null;
   obj['delayedRecallStoryAData'] = el.hasOwnProperty('delayedRecallStoryAData')?el['delayedRecallStoryAData'] :null;
   obj['phonologicalTotalData'] = el.hasOwnProperty('phonologicalTotalData')?el['phonologicalTotalData'] :null;

  return obj;
});