Iterating Over Nested Object in NodeJS

Question

How do I iterate over a dynamic nested object

{
  "2021-02-01": {
    "INR": 88.345,
    "CZK": 25.975,
    "JPY": 126.77
  },
  "2021-02-02": {
    "INR": 87.906,
    "CZK": 25.9,
    "JPY": 126.46
  },
  "2021-02-05": {
    "INR": 87.367,
    "CZK": 25.806,
    "JPY": 126.72
  }
}

Note: currency is dynamic it can change to other currency like here it is "INR, CZK, JPY" it can change to "USD, EUR, INR"

I need to get the value of all exchange rate of all currency in object and sum up all of them

here is what i have code (it is incomplete and i'm stuck in it)

      let rates = {here is object mentioned above}
     
      //iterating over object and pushing into array rateList
      for(let keys in rates){
            rateList.push(rates[keys])
      }
      
      //iterating over rateList array to get value
      rateList.forEach((obj)=>{
          console.log(Object.keys(obj)) //by this code i'm getting keys but how do i get value and sum it up
      })

Overall the objective is to get the average value of all exchange rate value.

esqew · Accepted Answer · 2021-02-17 05:52:47Z

2

Updated answer

Based on OP's comment below, there's still a shorthand-ish way to accomplish the requirement:

const rates = {
  "2021-02-01": {
    "INR": 88.345,
    "CZK": 25.975,
    "JPY": 126.77
  },
  "2021-02-02": {
    "INR": 87.906,
    "CZK": 25.9,
    "JPY": 126.46
  },
  "2021-02-05": {
    "INR": 87.367,
    "CZK": 25.806,
    "JPY": 126.72
  }
};

var returnObject = {};

Object.values(rates).forEach(childObject => { // loop all child objects within parent `rates` object:
    for (const [key, value] of Object.entries(childObject)) // extract each key=>value pair
      returnObject[key] = typeof returnObject[key] === 'undefined' ? value : returnObject[key] + value; // track it in `returnObject` - checks if the currency code already exists as a key in returnObject - if so, sums the current value and all previously-encountered values - if it doesn't already exist as a key in returnObject, sets the key to the current value
});

console.dir(returnObject);

Original answer

A shorthand-ish way of doing this would be:

const rates = { "2021-02-01": { "INR": 88.345, "CZK": 25.975, "JPY": 126.77 }, "2021-02-02": { "INR": 87.906, "CZK": 25.9, "JPY": 126.46 }, "2021-02-05": { "INR": 87.367, "CZK": 25.806, "JPY": 126.72 } }; for (var key of Object.keys(rates)) { // loop all dates in parent `rates` object: rates[key] = Object.values(rates[key]).reduce((acc, cv) => acc += cv); // extract the values for all keys in the child Object into an Array, then use reduce() to sum the values; finally, replace the initial child object with the float result of the summation } console.dir(rates);

Further reading:

Object.values()

Array.prototype.reduce()

edited Feb 17, 2021 at 5:52

answered Feb 17, 2021 at 3:51

esqew

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3 Comments

Mohammad Yunus Over a year ago

thanks for your response @esqew, I think I made mistake in my question. I need to sum up a particular currency like the sum of INR for a given date range your solution is doing sum of inr+czk+jpy but i need to find sum of 2021-02-05 {inr: 82} + 2021-02-04 {inr: 82} + 2021-02-03 {inr: 82} likewise to other currency

esqew Over a year ago

@MohammadYunus That makes sense, please edit your question to reflect & explain this better. I've updated my answer to reflect this new requirement.

Mohammad Yunus Over a year ago

I'll update my question, just one thing after sum up how can i get average of each? thanks @esqew

Mohammad Yaser Ahmadi · Accepted Answer · 2021-02-17 07:00:38Z

just try

let rates = {
  "2021-02-01": {
    "INR": 88.345,
    "CZK": 25.975,
    "JPY": 126.77
  },
  "2021-02-02": {
    "INR": 87.906,
    "CZK": 25.9,
    "JPY": 126.46
  },
  "2021-02-05": {
    "INR": 87.367,
    "CZK": 25.806,
    "JPY": 126.72
  }
}
let rateList = {};
let avarage = {}
//iterating over object and pushing into array rateList
for(let keys in rates){   
   Object.keys(rates[keys]).forEach((name , index)=>{
     if(rateList[name]){
    
      rateList[name]["avg"]  = (rateList[name]["avg"] + Object.values(rates[keys])[index] )/2
      rateList[name]["sum"]  += Object.values(rates[keys])[index]

     }
     else{
      let obj = {}
      obj.name = name;
      obj.sum =  Object.values(rates[keys])[index];
      obj.avg = Object.values(rates[keys])[index];
      rateList[name] = obj
     }
   }) 
}
rateList = Object.values(rateList)
console.log(rateList);

Bipin · Accepted Answer · 2021-02-17 03:41:44Z

0

let rates = {here is object mentioned above};//main object

var keys = Object.keys(rates);// Will return ["2021-02-01", "2021-02-02"]

for(let i = 0; i < keys.length;i++){
  var obj = rates[keys[i]];//will return nested object. {"INR": 88.345,"CZK": 25.975,"JPY": 126.77
  }
}

answered Feb 17, 2021 at 3:41

Bipin

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Comments

vincent · Accepted Answer · 2022-06-13 17:50:18Z

Here is an iterative solution using object-scan

.as-console-wrapper {max-height: 100% !important; top: 0}

<script type="module">
import objectScan from 'https://cdn.jsdelivr.net/npm/[email protected]/lib/index.min.js';

const data = { '2021-02-01': { INR: 88.345, CZK: 25.975, JPY: 126.77 }, '2021-02-02': { INR: 87.906, CZK: 25.9, JPY: 126.46 }, '2021-02-05': { INR: 87.367, CZK: 25.806, JPY: 126.72 } };

const aggregate = objectScan(['*.*'], {
  rtn: 'context',
  beforeFn: (state) => {
    // eslint-disable-next-line no-param-reassign
    state.context = {};
  },
  filterFn: ({ property, value, context }) => {
    if (!(property in context)) {
      context[property] = 0;
    }
    context[property] += value;
  }
});

console.log(aggregate(data));
// => { JPY: 379.95, CZK: 77.68100000000001, INR: 263.61800000000005 }
</script>

Disclaimer: I'm the author of object-scan

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