Determine the total number of values within a specific Object

Question

Determine the total number of values within a specific Object

const obj1 = {
  1: 'a',
  2: 'b',
  3: 'a',
  4: 'c',
  5: 'a',
  6: 'd',
  7: 'c',
};

The desired output for the given code should be:

output = { a: 3, b:  1, c: 2, d: 1 }

javascript arrays object

Answer 1

Answer №1

Success with this code!

function countOccurrences(obj) {
  const result = {};

  for (const key in obj) {
    const value = obj[key];
    result[value] = (result[value] || 0) + 1;
  }
  return result;
}
// Input object
const obj1 = {
  1: 'a',
  2: 'b',
  3: 'a',
  4: 'c',
  5: 'a',
  6: 'd',
  7: 'c'
};

// Execute the function
const output = countOccurrences(obj1);
console.log(output); // Result: { a: 3, b: 1, c: 2, d: 1 }

Answer 2

Success with this code!

function countOccurrences(obj) {
  const result = {};

  for (const key in obj) {
    const value = obj[key];
    result[value] = (result[value] || 0) + 1;
  }
  return result;
}
// Input object
const obj1 = {
  1: 'a',
  2: 'b',
  3: 'a',
  4: 'c',
  5: 'a',
  6: 'd',
  7: 'c'
};

// Execute the function
const output = countOccurrences(obj1);
console.log(output); // Result: { a: 3, b: 1, c: 2, d: 1 }

Answer 3

Answer №2

An efficient and concise solution can be implemented as follows:

Object.values(obj1).reduce((o,n)=>{
    if (!o[n]) o[n]=0;
    o[n]+=1;
    return o;
}, {})

The Object.values() method extracts the values of an object (refer to documentation for more information).

By utilizing the Array.protoype.reduce() function, we can apply a specified function on each element of the array and reduce it to a single value with an initial empty object {}. This distinguishes it from the Array.prototype.map method. (see documentation)

To enhance readability, I have chosen the parameter names o for old and n for new within the reduce function. The purpose of this operation is straightforward:

Check whether the key n (represented by a initially) exists in the current "old" value (initially an empty object {}). If not, assign a count of 0.
Increment the count at o[n] regardless.
Return the updated o.

In this case, the accumulator o is continuously passed into and returned by the function, accumulating the counts. Hence, it's often referred to as the accumulator. However, I find old more intuitive than accumulator.

Functions like Array.prototype.map, Array.protoype.reduce (and don't overlook Array.protoype.reduceRight) may seem complex initially, but they become invaluable tools once mastered.

Answer 4

An efficient and concise solution can be implemented as follows:

Object.values(obj1).reduce((o,n)=>{
    if (!o[n]) o[n]=0;
    o[n]+=1;
    return o;
}, {})

The Object.values() method extracts the values of an object (refer to documentation for more information).

By utilizing the Array.protoype.reduce() function, we can apply a specified function on each element of the array and reduce it to a single value with an initial empty object {}. This distinguishes it from the Array.prototype.map method. (see documentation)

To enhance readability, I have chosen the parameter names o for old and n for new within the reduce function. The purpose of this operation is straightforward:

Check whether the key n (represented by a initially) exists in the current "old" value (initially an empty object {}). If not, assign a count of 0.
Increment the count at o[n] regardless.
Return the updated o.

In this case, the accumulator o is continuously passed into and returned by the function, accumulating the counts. Hence, it's often referred to as the accumulator. However, I find old more intuitive than accumulator.

Functions like Array.prototype.map, Array.protoype.reduce (and don't overlook Array.protoype.reduceRight) may seem complex initially, but they become invaluable tools once mastered.

Determine the total number of values within a specific Object

Answer №1

Answer №2

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