Reduce & Spread an array of object values to a singular object with mapped [keyValue]: newValue pairs instead of [key]: value pairs.

SpreadReduceObject-NoArg.examples.ts

const dataMap = (data, valueArgs) => {
  return data
  .map( (obj) => ({
    date: new Date(obj.date),
    manual: true,
    ...valueArgs.reduce((prev, curr, index) => ({
      ...prev,
      [curr.name]: curr.split
                   ? Number(obj.value.split("/")[index])
                   : Number(obj.value),
    }), {}),
  }));
};

const noArgsData = [
  {
    date: "2020-01-31",
    value: "110",
  },
  {
    date: "2020-05-15",
    value: "80",
  },
];

const noArgsArr = [];
const noArgsExample = dataMap(noArgsData, noArgsArr);

console.log(noArgsExample);

/* 
[{
  date: [object Date] { ... },
  manual: true
}, {
  date: [object Date] { ... },
  manual: true
}]
*/

SpreadReduceObject-NoSplit.example.ts

/* Real world example */

const dataMap = (data, valueArgs) => {
  return data
  .map( (obj) => ({
    date: new Date(obj.date),
    manual: true,
    ...valueArgs.reduce((prev, curr, index) => ({
      ...prev,
      [curr.name]: curr.split
                   ? Number(obj.value.split("/")[index])
                   : Number(obj.value),
    }), {}),
  }));
};

const noSplitData = [
  {
    date: "2020-01-31",
    value: "110",
  },
  {
    date: "2020-05-15",
    value: "80",
  },
];

const noSplitArgsArr = [ { name: "latest", split: false } ];
const withoutSplit = dataMap(noSplitData, noSplitArgsArr);

console.log(withoutSplit);

//Output withoutSplit 
/* 
  [{
    date: [object Date] { ... },
    latest: 110,
    manual: true,
  }, {
    date: [object Date] { ... },
    latest: 80,
    manual: true,
	}]
*/

SpreadReduceObject-Simple.example.ts

/* Simple example */
const objArr = [{name: 0}, {name: 1}, {name: 2}];

const val = {
  ...objArr.reduce((prev, curr, index) => ({ ...prev, [curr.name]: index }), {}),
  "4": 3,
  "5": 4,
  "6": 5
};

//Output { 0: 0, 1: 1, 2: 2, 4: 3, 5: 4, 6: 5 }
console.log(val);

SpreadReduceObject-Split.example.ts

/* Real world example */

const dataMap = (data, valueArgs) => {
  return data
  .map( (obj) => ({
    date: new Date(obj.date),
    manual: true,
    ...valueArgs.reduce((prev, curr, index) => ({
      ...prev,
      [curr.name]: curr.split
                   ? Number(obj.value.split("/")[index])
                   : Number(obj.value),
    }), {}),
  }));
};

const splitData = [
  {
    date: "2020-01-31",
    value: "110/75",
  },
  {
    date: "2020-05-15",
    value: "80/120",
  },
];

const splitArgsArr = [ { name: "latest", split: true }, { name: "previous", split: true } ];
const withSplit = dataMap(splitData, splitArgsArr);

console.log(withSplit);

// Output with Split
/*
  [{
    date: [object Date] { ... },
    latest: 110,
    manual: true,
    previous: 75
  }, {
    date: [object Date] { ... },
    latest: 80,
    manual: true,
    previous: 120
  }]
*/