Looping through and getting frequency of all the elements in an array JavaScript

Let’s say, we will be given an array of numbers / strings that contains some duplicate entries, all we have to do is to return the frequency of each element in the array. Returning an object with element as key and it’s value as frequency would be perfect for this situation.

We will iterate over the array with a forEach() loop and keep increasing the count of elements in the object if it already exists otherwise we will create a new property for that element in the object.

And lastly, we will return the object.

The full code for this problem will be −

Example

const arr = [2,5,7,8,5,3,5,7,8,5,3,4,2,4,2,1,6,8,6];
const getFrequency = (array) => {
   const map = {};
   array.forEach(item => {
      if(map[item]){
         map[item]++;
      }else{
         map[item] = 1;
      }
   });
   return map;
};
console.log(getFrequency(arr));

Output

The output in the console will be −

{ '1': 1, '2': 3, '3': 2, '4': 2, '5': 4, '6': 2, '7': 2, '8': 3 }

AmitDiwan

Published on 19-Aug-2020 06:52:14

• Related Questions & Answers
• Looping through an array in Javascript
• Building frequency map of all the elements in an array JavaScript
• How to loop through all the elements of an array in C#?
• Getting elements of an array depending on corresponding values of another JavaScript
• Sum of all the non-repeating elements of an array JavaScript
• Looping through the content of a file in Bash
• Frequency of smaller and larger elements - JavaScript
• Return an array of all the indices of minimum elements in the array in JavaScript
• Frequency distribution of elements - JavaScript
• Sorting array according to increasing frequency of elements in JavaScript
• Sorting array based on increasing frequency of elements in JavaScript
• Frequency of elements of one array that appear in another array using JavaScript
• Looping numbers with object values and push output to an array - JavaScript?
• JavaScript Checking if all the elements are same in an array
• Looping through a dynamic table in SAP