JavaScript Program to Calculate the Frequency of Each Word in the Given String

Given a string, our task is to calculate the Frequency of Each Word in the Given String using JavaScript.

Example:

Input:
"geeks for geeks is for geeks"

Output:
"geeks": 3 ,  "for": 2 ,  "is": 1 

Below are the approaches for calculating the Frequency of Each Word in the Given String using JavaScript:

Using an Object

In this approach, Split the input string into an array of words and initialize an empty object frequency to store word frequencies. Use a loop to iterate through each word in the array of words and Check if the word already exists as a key in the frequency object. If it does not exist, initialize its frequency to 0. Increment the frequency count for the current word by 1. Return the frequency object.

Example: The example below shows how to Calculate the Frequency of Each Word in the Given String.

function wordFreqObj(str) {
    const words = str.split(/\s+/);
    const freq = {};
    words.forEach(word => {
        freq[word] = (freq[word] || 0) + 1;
    });
    return freq;
}

const str = "geeks for geeks is for geeks";
console.log(wordFreqObj(str));

{ geeks: 3, for: 2, is: 1 }

Time Complexity: O(n + m)

Space Complexity: O(n + m)

Using Map

In this approach, Split the input string into an array of words and initialize a frequency to new map to store word frequencies. Use a loop to iterate through each word and Check if the word already exists as a key in the Map frequency. If it does not exist, initialize its frequency to 0. Increment the frequency count for the current word by 1 using the set() method of Map. Return the frequency Map.

Example: The example below show how to Calculate the Frequency of Each Word in the Given String.

function wordFreqMap(str) {
    const words = str.split(/\s+/);

    // Create a Map to Store Word Frequencies
    const freq = new Map();

    // Iterate Through the Array of Words
    words.forEach(word => {
        freq.set(word, (freq.get(word) || 0) + 1);
    });

    return freq;
}

const str = "geeks for geeks is for geeks";
console.log(wordFreqMap(str));

Map(3) { 'geeks' => 3, 'for' => 2, 'is' => 1 }

Time Complexity: O(n + m)

Space Complexity: O(n + m)

Using reduce with an Object

In this approach, we use the reduce method to iterate through the array of words and build the frequency object. This method is a bit more functional and concise compared to using a loop.

1. Split the input string into an array of words.
2. Use the reduce method to build the frequency object by iterating through each word.
3. Check if the word already exists as a key in the frequency object. If it does not exist, initialize its frequency to 0.
4. Increment the frequency count for the current word by 1.
5. Return the frequency object.

Example:

function wordFreqReduce(str) {
    const words = str.split(/\s+/);
    const freq = words.reduce((acc, word) => {
        acc[word] = (acc[word] || 0) + 1;
        return acc;
    }, {});
    return freq;
}

const str = "geeks for geeks is for geeks";
console.log(wordFreqReduce(str));

{ geeks: 3, for: 2, is: 1 }