JavaScript: Number of occurrences of each letter in specified string

JavaScript Function: Exercise-17 with Solution

Count Letter Occurrences

Write a JavaScript function to get the number of occurrences of each letter in a specified string.

Visual Presentation:

Sample Solution-1:

JavaScript Code:

// Define a function named Char_Counts that counts the occurrences of each character in the input string
function Char_Counts(str1) {
  // Create an empty object uchars to store character counts
  var uchars = {};

  // Use the replace method to iterate through each non-whitespace character in the input string
  str1.replace(/\S/g, function(l) {
    // Check if the current character is already in the uchars object
    uchars[l] = (isNaN(uchars[l]) ? 1 : uchars[l] + 1);
  });

  // Return the object containing character counts
  return uchars;
}

// Log the result of calling Char_Counts with the input string "The quick brown fox jumps over the lazy dog" to the console
console.log(Char_Counts("The quick brown fox jumps over the lazy dog")); 

Output:

{"T":1,"h":2,"e":3,"q":1,"u":2,"i":1,"c":1,"k":1,"b":1,"r":2,"o":4,"w":1,"n":1,"f":1,"x":1,"j":1,"m":1,"p":1,"s":1,"v":1,"t":1,"l":1,"a":1,"z":1,"y":1,"d":1,"g":1}

Flowchart:

Live Demo:

See the Pen JavaScript - Number of occurrences of each letter in specified string-function-ex- 17 by w3resource (@w3resource) on CodePen.

Sample Solution-2:

JavaScript Code:

// Function to count occurrences of each letter in a string
function countLetterOccurrences(str) {
    // Initialize an empty object to store letter occurrences
    const letterOccurrences = {};

    // Convert the string to lowercase to make the counting case-insensitive
    const lowercaseStr = str.toLowerCase();

    // Iterate through each character in the lowercase string
    for (let char of lowercaseStr) {
        // Check if the character is an alphabet letter
        if (/^[a-z]$/.test(char)) {
            // Update or initialize the count for the current letter
            letterOccurrences[char] = (letterOccurrences[char] || 0) + 1;
        }
    }

    return letterOccurrences;
}

// Example usage:
const inputString = "The quick brown fox jumps over the lazy dog.";
const result = countLetterOccurrences(inputString);

// Log the result to the console
console.log(result); 

Output:

{"t":2,"h":2,"e":3,"q":1,"u":2,"i":1,"c":1,"k":1,"b":1,"r":2,"o":4,"w":1,"n":1,"f":1,"x":1,"j":1,"m":1,"p":1,"s":1,"v":1,"l":1,"a":1,"z":1,"y":1,"d":1,"g":1}

Flowchart:

For more Practice: Solve these Related Problems:

• Write a JavaScript function that counts the occurrences of each letter in a string and returns an object mapping letters to counts.
• Write a JavaScript function that counts letter occurrences in a string while ignoring case and special characters.
• Write a JavaScript function that uses the array reduce method to count how many times each letter appears in a string.
• Write a JavaScript function that counts letter occurrences and identifies the most frequently occurring letter along with its count.

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