JavaScript: Find the number which appears most in a given array of integers

JavaScript Basic: Exercise-94 with Solution

Find Most Frequent Number in Array

Write a JavaScript program to find the number appearing most frequently in a given array of integers.

Visual Presentation:

Sample Solution:

JavaScript Code:

// Function to find the mode (most frequently occurring element) in an array
function array_element_mode(arr) {
  var ctr = [],  // Counter array to store frequencies of elements
    ans = 0;     // Variable to store the index of the mode

  // Initialize the counter array with zeros for each possible element
  for (var i = 0; i < 10; i++) {
    ctr.push(0);
  }

  // Iterate through the input array to update the frequencies in the counter array
  for (var i = 0; i < arr.length; i++) {
    ctr[arr[i] - 1]++;  // Increment the frequency of the current element
    if (ctr[arr[i] - 1] > ctr[ans]) {
      ans = arr[i] - 1;  // Update the index of the mode if a higher frequency is found
    }
  }

  return ans + 1;  // Return the mode (add 1 to convert from zero-based index to element value)
}

// Example usage
console.log(array_element_mode([1, 2, 3, 2, 2, 8, 1, 9]));  // 2

Output:

2

Live Demo:

See the Pen javascript-basic-exercise-94 by w3resource (@w3resource) on CodePen.

Flowchart:

ES6 Version:

// Function to find the mode (most frequent element) in an array
const array_element_mode = (arr) => {
    let ctr = [];  // Array to store the count of each element
    let ans = 0;    // Variable to store the index with the highest count

    // Initialize the count array with zeros for each possible element (1 to 10)
    for (let i = 0; i < 10; i++) {
        ctr.push(0);
    }

    // Iterate through the input array to count occurrences of each element
    for (let i = 0; i < arr.length; i++) {
        ctr[arr[i] - 1]++;  // Increment the count for the corresponding element
        if (ctr[arr[i] - 1] > ctr[ans]) {
            ans = arr[i] - 1;  // Update the index with the highest count
        }
    }

    return ans + 1;  // Return the mode (element with the highest count)
};

// Example usage
console.log(array_element_mode([1, 2, 3, 2, 2, 8, 1, 9]));  

For more Practice: Solve these Related Problems:

• Write a JavaScript program that builds a frequency map from an array of integers and returns the number that appears most frequently.
• Write a JavaScript function that identifies the mode in an array of numbers, handling cases with multiple modes by returning the smallest.
• Write a JavaScript program that iterates through an array to determine the most common number, and returns both the number and its frequency.

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