Obtain the initial data value and store it in an array for each distinct date

Question

Obtain the initial data value and store it in an array for each distinct date

Below is a data object that needs to be iterated through using JavaScript in order to extract one "value" field into an array for each unique date.

While I am able to retrieve all the data, my goal is to collect one value for each distinct date (ignoring the time component).

{
  name: "test", 
  data: Array(200)
}

data: Array(200) 
0: {
  @id: "p23o"
  code: "02"
  dateTime: "2018-12-12T04:38:00Z"
  value: -0.645
}  
1: {
  @id: "p453o"
  code: "02"
  dateTime: "2018-12-12T07:48:00Z"
  value: -0.3645
} 
2: {
  @id: "p4423o"
  code: "032"
  dateTime: "2018-12-11T07:13:00Z"
  value: -0.645
} 
+ 198 more objects

The resulting array should contain one value per day. What is the correct way to iterate over this data and create the desired array? Are there any best practices or recommended methods for accomplishing this task?

Thank you for your help!

javascript arrays

Answer 1

Answer №1

Transform your date string into a Date object using the Date constructor, then strip the time from the date.

Follow the code below:

// Your response data will be stored in the variable 'data'
var uniqueData = {};
data.forEach(item => {
   var date = new Date(item.dateTime);  
   var onlyDaysTime = new Date(date.getYear(), date.getMonth(), 
       date.getDate());
   var key = onlyDaysTime.toString();

   if(typeof uniqueData[key] === 'undefined') {
      uniqueData[key] = [];
   }
   uniqueData[key].push(item);
})

for(key in uniqueData) {
  console.log(uniqueData[key]);
}

Output:

[[object Object] {
  code: "02",
  dateTime: "2018-12-12T04:38:00Z",
  id: "p23o",
  value: -0.645
}, [object Object] {
  code: "02",
  dateTime: "2018-12-12T07:48:00Z",
  id: "p453o",
  value: -0.3645
}]
[[object Object] {
  code: "032",
  dateTime: "2018-12-11T07:13:00Z",
  id: "p4423o",
  value: -0.645
}]

Try it out on JSBin: https://jsbin.com/juwekiduju/edit?js,console

Answer 2

Transform your date string into a Date object using the Date constructor, then strip the time from the date.

Follow the code below:

// Your response data will be stored in the variable 'data'
var uniqueData = {};
data.forEach(item => {
   var date = new Date(item.dateTime);  
   var onlyDaysTime = new Date(date.getYear(), date.getMonth(), 
       date.getDate());
   var key = onlyDaysTime.toString();

   if(typeof uniqueData[key] === 'undefined') {
      uniqueData[key] = [];
   }
   uniqueData[key].push(item);
})

for(key in uniqueData) {
  console.log(uniqueData[key]);
}

Output:

[[object Object] {
  code: "02",
  dateTime: "2018-12-12T04:38:00Z",
  id: "p23o",
  value: -0.645
}, [object Object] {
  code: "02",
  dateTime: "2018-12-12T07:48:00Z",
  id: "p453o",
  value: -0.3645
}]
[[object Object] {
  code: "032",
  dateTime: "2018-12-11T07:13:00Z",
  id: "p4423o",
  value: -0.645
}]

Try it out on JSBin: https://jsbin.com/juwekiduju/edit?js,console

Answer 3

Answer №2

To effectively store the object corresponding to each unique date in an object accumulator, you can utilize array#reduce. Subsequently, all values from this object can be retrieved using Object.values()

let data = [{ "@id": "p23o", code: "02", dateTime: "2018-12-12T04:38:00Z", value: -0.645 } , { "@id": "p453o", code: "02", dateTime: "2018-12-12T07:48:00Z", value: -0.3645 } , { "@id": "p4423o", code: "032", dateTime: "2018-12-11T07:13:00Z", value: -0.645 }],
    result = Object.values(data.reduce((r,o) => {
      let date = o.dateTime.substring(0,10);
      if(!(date in r)) r[date] = {...o};
      return r;
    },{}));
console.log(result);

Answer 4

To effectively store the object corresponding to each unique date in an object accumulator, you can utilize array#reduce. Subsequently, all values from this object can be retrieved using Object.values()

let data = [{ "@id": "p23o", code: "02", dateTime: "2018-12-12T04:38:00Z", value: -0.645 } , { "@id": "p453o", code: "02", dateTime: "2018-12-12T07:48:00Z", value: -0.3645 } , { "@id": "p4423o", code: "032", dateTime: "2018-12-11T07:13:00Z", value: -0.645 }],
    result = Object.values(data.reduce((r,o) => {
      let date = o.dateTime.substring(0,10);
      if(!(date in r)) r[date] = {...o};
      return r;
    },{}));
console.log(result);

Obtain the initial data value and store it in an array for each distinct date

Answer №1

Answer №2

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