JavaScript: Change the capitalization of all letters in a given string

JavaScript Basic: Exercise-149 with Solution

Write a JavaScript program to change the capitalization of all letters in a given string.

Visual Presentation:

Sample Solution:

JavaScript Code:

/**
 * Function to change the case of characters in a string
 * @param {string} txt - The input string
 * @returns {string} - The string with changed case characters
 */
function change_case(txt) {
    var str1 = "";
    // Loop through each character in the input string
    for (var i = 0; i < txt.length; i++) {
        // Check if the character is uppercase, change to lowercase; otherwise, change to uppercase
        if (/[A-Z]/.test(txt[i])) str1 += txt[i].toLowerCase();
        else str1 += txt[i].toUpperCase();
    }
    return str1; // Return the modified string
}

// Test cases
console.log(change_case("w3resource")); // Output: W3RESOURCE
console.log(change_case("Germany")); // Output: gERMANY

Output:

W3RESOURCE
gERMANY

Live Demo:

See the Pen javascript-basic-exercise-149 by w3resource (@w3resource) on CodePen.

Flowchart:

ES6 Version:

/**
 * Function to change the case of characters in a string
 * @param {string} txt - The input string
 * @returns {string} - The string with changed case characters
 */
const change_case = (txt) => {
    let str1 = "";
    // Loop through each character in the input string
    for (let i = 0; i < txt.length; i++) {
        // Check if the character is uppercase, change to lowercase; otherwise, change to uppercase
        if (/[A-Z]/.test(txt[i])) str1 += txt[i].toLowerCase();
        else str1 += txt[i].toUpperCase();
    }
    return str1; // Return the modified string
}

// Test cases
console.log(change_case("w3resource")); // Output: W3RESOURCE
console.log(change_case("Germany")); // Output: gERMANY

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