w3resource

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.

Pictorial Presentation:

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

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>Change the capitalization of all letters in a given string.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function change_case(txt) {
    var str1 = "";
    for (var i = 0; i < txt.length; i++) {
        if (/[A-Z]/.test(txt[i])) str1 += txt[i].toLowerCase();
        else str1 += txt[i].toUpperCase();
    }
    return str1;
}

console.log(change_case("w3resource"));
console.log(change_case("Germany"));

Sample Output:

W3RESOURCE
gERMANY

Flowchart:

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

ES6 Version:

function change_case(txt) {
    let str1 = "";
    for (let i = 0; i < txt.length; i++) {
        if (/[A-Z]/.test(txt[i])) str1 += txt[i].toLowerCase();
        else str1 += txt[i].toUpperCase();
    }
    return str1;
}

console.log(change_case("w3resource"));
console.log(change_case("Germany"));

Live Demo:

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


Improve this sample solution and post your code through Disqus

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Next: Write a JavaScript program to find the difference of the two given sets.

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JavaScript: Tips of the Day

Parameter's value

function getItems(fruitList, ...args, favoriteFruit) {
  return [...fruitList, ...args, favoriteFruit]
}

getItems(["banana", "apple"], "pear", "orange")

...args is a rest parameter. The rest parameter's value is an array containing all remaining arguments, and can only be the last parameter! In this example, the rest parameter was the second parameter. This is not possible, and will throw a syntax error.

function getItems(fruitList, favoriteFruit, ...args) {
  return [...fruitList, ...args, favoriteFruit];
}


getItems(['banana', 'apple'], 'pear', 'orange');
The above example works. This returns the array [ 'banana', 'apple', 'orange', 'pear' ].

Ref: https://bit.ly/3jFRBje