How to sum values of certain properties for each subgroup nested array object's in Javascript?-CodePudding

From the object below, I wanted to sum up certain properties (fare tax and com agency) by their key group (1345, 2353).

var details = [{ 1345:[
                {route: 34, fare: 45, tax: 46, date: 46, com: 45, agency: 24, totalCost: 0, totalFee: 0}], 
               2353: [
                {route: 32, fare: 45, tax: 45, date: 56, com: 34, agency: 52, totalCost: 0, totalFee: 0}, 
                {route: 42, fare: 34, tax: 64, date: 34, com: 56, agency: 34, totalCost: 0, totalFee: 0}
              ]} 
             ]

expected output:

1345: { ..., totalCost: 91, totalFee: 69 }
2353: {..., totalCost: 188, totalFee: 90 }

totalCost = fare tax and totalFee = com agency

I tried to simplified the array objects and convert by using Object.entries(details[0]), then reduce to sum up the target properties.

Object.entries(details[0]).reduce((acc, curr) => (acc = acc   curr["fare"] curr["tax"]), 0);

However, NaN was returned.

Would appreciate if anyone could show me how I can loop through each key group and sum up the target values and update it (totalCost and totalFee).

CodePudding user response：

One way (of many) would be to initialize a totals object in the format you want.

const totals = {}

for (const key in details[0]) {
  totals[key] = {
    totalCost: 0,
    totalFee: 0,
  }
}

Then use a simple sum function to sum up an arbitrary array of values:

function sum(...nums) {
  return nums.reduce((acc, val) => acc   val)
}

The rest is pretty simple: Sum based on your totalCost/totalFee logic:

for (const [key, vals] of Object.entries(details[0])) {
  totals[key].totalCost = sum(...vals.map(val => val.fare   val.tax))
  totals[key].totalFee  = sum(...vals.map(val => val.com   val.agency))
}

Here's the whole shebang:

const details = [
  {
    1345: [
      {route: 34, fare: 45, tax: 46, date: 46, com: 45, agency: 24, totalCost: 0, totalFee: 0},
    ], 
    2353: [
      {route: 32, fare: 45, tax: 45, date: 56, com: 34, agency: 52, totalCost: 0, totalFee: 0}, 
      {route: 42, fare: 34, tax: 64, date: 34, com: 56, agency: 34, totalCost: 0, totalFee: 0},
    ],
  },
]

const totals = {}

for (const key in details[0]) {
  totals[key] = {
    totalCost: 0,
    totalFee: 0,
  }
}

for (const [key, vals] of Object.entries(details[0])) {
  totals[key].totalCost = sum(...vals.map(val => val.fare   val.tax))
  totals[key].totalFee  = sum(...vals.map(val => val.com   val.agency))
}

console.log(totals)

function sum(...nums) {
  return nums.reduce((acc, val) => acc   val)
}

CodePudding user response：

We can do this using a few Array.reduce() calls, the end result should be as required.

For each key group, we'd use Object.entries() to get the key and value for the group.

const details = [{ 1345:[ {route: 34, fare: 45, tax: 46, date: 46, com: 45, agency: 24, totalCost: 0, totalFee: 0}], 2353: [ {route: 32, fare: 45, tax: 45, date: 56, com: 34, agency: 52, totalCost: 0, totalFee: 0}, {route: 42, fare: 34, tax: 64, date: 34, com: 56, agency: 34, totalCost: 0, totalFee: 0} ]} ]
         
const result = details.reduce((acc, group) => { 
    return Object.entries(group).reduce((acc, [key, routes] ) => {
        return routes.reduce((acc, { fare, tax, com, agency}) => { 
            acc[key] = acc[key] || {};
            acc[key].totalCost = (acc[key].totalCost || 0)   fare   tax;
            acc[key].totalFee = (acc[key].totalFee || 0)   com   agency;
            return acc;
        }, acc)
    }, acc)
}, {})

console.log('Result:', result)

.as-console-wrapper { max-height: 100% !important; }

CodePudding user response：

Expanding on the use of Object.values

var details = [{ 1345:[
                {route: 34, fare: 45, tax: 46, date: 46, com: 45, agency: 24, totalCost: 0, totalFee: 0}], 
               2353: [
                {route: 32, fare: 45, tax: 45, date: 56, com: 34, agency: 52, totalCost: 0, totalFee: 0}, 
                {route: 42, fare: 34, tax: 64, date: 34, com: 56, agency: 34, totalCost: 0, totalFee: 0}
              ]} 
             ]

Object.values(details).map(x => {
  details = []
  let count = 0;
  for (let y of Object.values(x)) {
    y = y.reduce(function (a, b) {
      for (const key in b) {
        if (a[key]) {
          a[key] = a[key]   b[key]
        } else {
          a[key] = b[key];
        }
      }
      return a;
    }, {});
    y['totalCost'] = y['fare']   y['tax']; 
    y['totalFee'] = y['com']   y['agency'];
    let totalObj = {};
    totalObj[`${Object.keys(x)[count]}`] = `totalCost: ${y['totalCost']}, totalFee: ${y['totalFee']}` 
    details.push(totalObj)
    count  ;
  };
});

console.log(details);