JavaScript: Input a string and converts upper case letters to lower and vice versa

Last update on May 30 2022 10:02:30 (UTC/GMT +8 hours)

JavaScript String: Exercise-10 with Solution

Write a JavaScript function that takes a string which has lower and upper case letters as a parameter and converts upper case letters to lower case, and lower case letters to upper case.

Test Data:
console.log(swapcase('AaBbc'));
"aAbBC"

Pictorial Presentation:

JavaScript: Input a string and converts upper case letters to lower and vice versa

Sample Solution:-

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS swap case</title>
</head>
<body>
</body>
</html>

JavaScript Code:

swapcase = function swapcase(str) {
        return str.replace(/([a-z]+)|([A-Z]+)/g, function(match, chr) {
            return chr ? match.toUpperCase() : match.toLowerCase();
        });
    }
console.log(swapcase('AaBbc'));

Sample Output:

aAbBC

Flowchart:

Live Demo:

See the Pen JavaScript Input a string and converts upper case letters to lower and vice versa - string-ex-10 by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04