Q331- Find frequency of each element in an array in JavaScript?

You can find the frequency of each element in an array using a few common JavaScript approaches.

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✅ 1. Using reduce() (Most Preferred)

const arr = ["apple", "banana", "apple", "orange", "banana", "apple"];

const freq = arr.reduce((acc, item) => {
  acc[item] = (acc[item] || 0) + 1;
  return acc;
}, {});

console.log(freq);

🔹 Output

{
  apple: 3,
  banana: 2,
  orange: 1
}

🧠 Why it works

• reduce loops once
• Object stores counts
• Efficient and clean

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✅ 2. Using a for loop

const freq = {};
for (let item of arr) {
  freq[item] = (freq[item] || 0) + 1;
}

✔ Easy to understand
✔ Good for beginners

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✅ 3. Using Map (Best for non-string keys)

const freqMap = new Map();

for (let item of arr) {
  freqMap.set(item, (freqMap.get(item) || 0) + 1);
}

console.log(Object.fromEntries(freqMap));

✔ Preserves order
✔ Works with objects too

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🎯 Short Interview Answer

To find frequency, iterate through the array and store counts in an object or Map. Each time an element appears, increment its count.

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⭐ One-line summary

Use reduce() or a loop to count how many times each element appears in an array.