Total the values of specific properties in an array of objects when another property meets a specified criterion

Question

Total the values of specific properties in an array of objects when another property meets a specified criterion

I've been attempting to calculate the total sum of account balances for accounts labeled as "Savings", but my current approach seems to be unsuccessful. My initial plan was to iterate through the array using a forEach loop and then check if the account type is classified as savings, however I'm encountering some issues.

const accounts = [
    {acctNo: 123, type: 'Checking', balance: 150},
    {acctNo: 234, type: 'Checking', balance: 200},
    {acctNo: 345, type: 'Savings', balance: 550},
    {acctNo: 456, type: 'Checking', balance: 550},
    {acctNo: 567, type: 'Savings', balance: 1500}
];
const sum = accounts.forEach(function(account){
  if (account.type === 'Savings'){
    account.reduce(function(a,b){
      return {balance: a.balance + b.balance};
    });
  }
});

console.log(sum);

javascript arrays iterator

Answer 1

Answer №1

When using a forEach loop, you are unable to return any values. Additionally, performing a reduce operation directly on accounts may not be the most logical approach. Consider utilizing filter and map methods instead, ensuring that you perform the reduce operation on a list:

accounts.filter(account => account.type === 'Savings')
    .map(account => account.balance)
    .reduce((accumulator, currentValue) => accumulator + currentValue)

Answer 2

When using a forEach loop, you are unable to return any values. Additionally, performing a reduce operation directly on accounts may not be the most logical approach. Consider utilizing filter and map methods instead, ensuring that you perform the reduce operation on a list:

accounts.filter(account => account.type === 'Savings')
    .map(account => account.balance)
    .reduce((accumulator, currentValue) => accumulator + currentValue)

Answer 3

Answer №2

Here is a method to achieve this task by combining several array functions:

1) Begin by using the filter function to extract only the accounts categorized as 'Savings'

2) Next, utilize the map function to isolate and gather the account balances

3) Finally, sum up the obtained array values. In this example, I have used the reduce function in conjunction with map and filter. However, you could also accomplish this by manually iterating through the array and keeping track of the total balance if that is your preference

It is worth noting that arrow functions are employed here for succinctness and clarity. Nevertheless, traditional function() { ... } expressions can be substituted without altering functionality.

const accounts = [
    {acctNo: 123, type: 'Checking', balance: 150},
    {acctNo: 234, type: 'Checking', balance: 200},
    {acctNo: 345, type: 'Savings', balance: 550},
    {acctNo: 456, type: 'Checking', balance: 550},
    {acctNo: 567, type: 'Savings', balance: 1500}
];

const sum = accounts.filter(account => account.type === 'Savings')
                    .map(account => account.balance)
                    .reduce((acc, bal) => acc + bal);

console.log(sum)

Answer 4

Here is a method to achieve this task by combining several array functions:

1) Begin by using the filter function to extract only the accounts categorized as 'Savings'

2) Next, utilize the map function to isolate and gather the account balances

3) Finally, sum up the obtained array values. In this example, I have used the reduce function in conjunction with map and filter. However, you could also accomplish this by manually iterating through the array and keeping track of the total balance if that is your preference

It is worth noting that arrow functions are employed here for succinctness and clarity. Nevertheless, traditional function() { ... } expressions can be substituted without altering functionality.

const accounts = [
    {acctNo: 123, type: 'Checking', balance: 150},
    {acctNo: 234, type: 'Checking', balance: 200},
    {acctNo: 345, type: 'Savings', balance: 550},
    {acctNo: 456, type: 'Checking', balance: 550},
    {acctNo: 567, type: 'Savings', balance: 1500}
];

const sum = accounts.filter(account => account.type === 'Savings')
                    .map(account => account.balance)
                    .reduce((acc, bal) => acc + bal);

console.log(sum)

Answer 5

Answer №3

reduce functions as an array method, not an object method.

Using both forEach and reduce is unnecessary. The reduce method already iterates over the array, simply include the if condition within the function.

const accounts = [
    {acctNo: 123, type: 'Checking', balance: 150},
    {acctNo: 234, type: 'Checking', balance: 200},
    {acctNo: 345, type: 'Savings', balance: 550},
    {acctNo: 456, type: 'Checking', balance: 550},
    {acctNo: 567, type: 'Savings', balance: 1500}
];
const sum = accounts.reduce(function(a, account){
  if (account.type === 'Savings'){
    return a + account.balance;
  } else {
    return a;
  }
}, 0)

console.log(sum)

Answer 6

reduce functions as an array method, not an object method.

Using both forEach and reduce is unnecessary. The reduce method already iterates over the array, simply include the if condition within the function.

const accounts = [
    {acctNo: 123, type: 'Checking', balance: 150},
    {acctNo: 234, type: 'Checking', balance: 200},
    {acctNo: 345, type: 'Savings', balance: 550},
    {acctNo: 456, type: 'Checking', balance: 550},
    {acctNo: 567, type: 'Savings', balance: 1500}
];
const sum = accounts.reduce(function(a, account){
  if (account.type === 'Savings'){
    return a + account.balance;
  } else {
    return a;
  }
}, 0)

console.log(sum)

Answer 7

Answer №4

Responding to @RobinZigmond's inquiry

filter function is applied to eliminate all non-'Savings' accounts from the array and returns an array of those with type === 'savings'. The resulting array is then passed to the map method.

map operation generates a new array containing only the balances of the savings accounts. Subsequently, this array is handed over to the reduce process.

reduce simplifies multiple elements in an array into a single value. In our context, it takes the array of balances, sums them up, and assigns the result to sum.

const accounts = [
  { acctNo: 123, type: 'Checking', balance: 150 },
  { acctNo: 234, type: 'Checking', balance: 200 },
  { acctNo: 345, type: 'Savings', balance: 550 },
  { acctNo: 456, type: 'Checking', balance: 550 },
  { acctNo: 567, type: 'Savings', balance: 1500 }
];

const sum = accounts
  .filter((account) => account.type.toLowerCase() === 'savings')
  .map((savingsAccounts) => savingsAccounts.balance)
  .reduce((accumulator, balance) => accumulator + balance);

console.log(sum);

Answer 8

Responding to @RobinZigmond's inquiry

filter function is applied to eliminate all non-'Savings' accounts from the array and returns an array of those with type === 'savings'. The resulting array is then passed to the map method.

map operation generates a new array containing only the balances of the savings accounts. Subsequently, this array is handed over to the reduce process.

reduce simplifies multiple elements in an array into a single value. In our context, it takes the array of balances, sums them up, and assigns the result to sum.

const accounts = [
  { acctNo: 123, type: 'Checking', balance: 150 },
  { acctNo: 234, type: 'Checking', balance: 200 },
  { acctNo: 345, type: 'Savings', balance: 550 },
  { acctNo: 456, type: 'Checking', balance: 550 },
  { acctNo: 567, type: 'Savings', balance: 1500 }
];

const sum = accounts
  .filter((account) => account.type.toLowerCase() === 'savings')
  .map((savingsAccounts) => savingsAccounts.balance)
  .reduce((accumulator, balance) => accumulator + balance);

console.log(sum);

Total the values of specific properties in an array of objects when another property meets a specified criterion

Answer №1

Answer №2

Answer №3

Answer №4

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