合并2个javascript数组

我有两个阵列：

const calendar = [
    {"_id":"Jan"}, {"_id":"Feb"}, {"_id":"Mar"},
    {"_id":"Apr"}, {"_id":"May"}, {"_id":"Jun"},
    {"_id":"Jul"}, {"_id":"Aug"}, {"_id":"Sep"},
    {"_id":"Oct"}, {"_id":"Nov"}, {"_id":"Dec"}
]

及

我希望合并这两个数组，以便在当月没有计数时，将其设置为“计数”：0

例如，新阵列应如下所示：

const final = [
    {"_id":"Jan","count":1}, {"_id":"Feb","count":1},
    {"_id":"Mar","count":2}, {"_id":"Apr","count":6},
    {"_id":"May","count":5}, {"_id":"Jun","count":2},
    {"_id":"Jul","count":1}, {"_id":"Aug","count":0},
    {"_id":"Sep","count":0}, {"_id":"Oct","count":0},
    {"_id":"Nov","count":0}, {"_id":"Dec","count":0}
]

我对此有点迷茫。非常感谢任何人的帮助

---

谢谢

首先创建一个ID到计数的映射。然后将所有日历月映射到已创建映射中的计数，如果不存在，则默认为0

var countMap = {};
count.forEach((a) => {
    countMap[a._id] = a.count
});

const final = calendar.map((month) => ({_id: month._id, count: countMap[month._id] ||0}))

您可以在此处看到一个正在工作的exmaple:

您可以使用a并首先进行所有计数。然后映射新对象

var calendar=[{id:“一月”}、{id:“二月”}、{id:“三月”}、{id:“四月”}、{id:“五月”}、{id:“六月”}、{id:“七月”}、{id:“八月”}、{id:“九月”}、{id:“十月”}、{id:“十一月”}、{id:“十二月”}，
count=[{id:“一月”，count:1}，{id:“四月”，count:6}，{id:“五月”，count:5}，{id:“二月”，count:1}，{id:“七月”，count:1}，{id:“三月”，count:2}，{id:“六月”，count:2}]，
map=newmap（count.map（o=>[o.\u id，o.count]），
final=calendar.map（o=>Object.assign（{}，o，{count:map.get（o.|u id）| 0}））；
控制台日志（最终）
.as控制台包装{max height:100%！important；top:0；}
这将为您提供：

const calendar = [{
  "_id": "Jan"
}, {
  "_id": "Feb"
}, {
  "_id": "Mar"
}, {
  "_id": "Apr"
}, {
  "_id": "May"
}, {
  "_id": "Jun"
}, {
  "_id": "Jul"
}, {
  "_id": "Aug"
}, {
  "_id": "Sep"
}, {
  "_id": "Oct"
}, {
  "_id": "Nov"
}, {
  "_id": "Dec"
}];

const count = [{
  "_id": "Jan",
  "count": 1
}, {
  "_id": "Apr",
  "count": 6
}, {
  "_id": "May",
  "count": 5
}, {
  "_id": "Feb",
  "count": 1
}, {
  "_id": "Jul",
  "count": 1
}, {
  "_id": "Mar",
  "count": 2
}, {
  "_id": "Jun",
  "count": 2
}]

var result = [];
for (var mth = 0; mth < calendar.length; mth++) {
  var ct = 0;
  for (var mthCt = 0; mthCt < count.length; mthCt++) {
    if (calendar[mth]._id === count[mthCt]._id) {
      ct = count[mthCt].count;
    }
  }
  result[mth] = {
    "id": calendar[mth]._id,
    "count": ct
  }
}
document.getElementById('output').textContent = JSON.stringify(result);

const日历=[{
“_id”：“Jan”
}, {
_id:“二月”
}, {
“_id”：“Mar”
}, {
_id:“Apr”
}, {
“_id”：“May”
}, {
_id:“Jun”
}, {
“_id”：“七月”
}, {
_id:“八月”
}, {
“_id”：“Sep”
}, {
_id:“十月”
}, {
“\u id”：“11月”
}, {
_id:“Dec”
}];
常数计数=[{
“_id”：“Jan”，
“计数”：1
}, {
“_id”：“Apr”，
“计数”：6
}, {
“_id”：“May”，
“计数”：5
}, {
“_id”：“Feb”，
“计数”：1
}, {
“_id”：“七月”，
“计数”：1
}, {
“_id”：“Mar”，
“计数”：2
}, {
“_id”：“Jun”，
“计数”：2
}]
var结果=[]；
对于（var mth=0；mth

请尝试使用数组函数，如
const calendar = [{
  "_id": "Jan"
}, {
  "_id": "Feb"
}, {
  "_id": "Mar"
}, {
  "_id": "Apr"
}, {
  "_id": "May"
}, {
  "_id": "Jun"
}, {
  "_id": "Jul"
}, {
  "_id": "Aug"
}, {
  "_id": "Sep"
}, {
  "_id": "Oct"
}, {
  "_id": "Nov"
}, {
  "_id": "Dec"
}];

const count = [{
  "_id": "Jan",
  "count": 1
}, {
  "_id": "Apr",
  "count": 6
}, {
  "_id": "May",
  "count": 5
}, {
  "_id": "Feb",
  "count": 1
}, {
  "_id": "Jul",
  "count": 1
}, {
  "_id": "Mar",
  "count": 2
}, {
  "_id": "Jun",
  "count": 2
}]

var result = [];
for (var mth = 0; mth < calendar.length; mth++) {
  var ct = 0;
  for (var mthCt = 0; mthCt < count.length; mthCt++) {
    if (calendar[mth]._id === count[mthCt]._id) {
      ct = count[mthCt].count;
    }
  }
  result[mth] = {
    "id": calendar[mth]._id,
    "count": ct
  }
}
document.getElementById('output').textContent = JSON.stringify(result);