How to Convert a String to Uppercase and Lowercase in JavaScript

Updated on by Alan Morel @AlanMorelX
How to Convert a String to Uppercase and Lowercase in JavaScript

When you work with strings in any programming language, you'll often need to change the case of the string.

That can be either turning the entire string to uppercase or lowercase.

Thankfully, JavaScript makes it easy to transform your string between these two cases.

In this post, we'll learn how to convert a string to uppercase or lowercase in JavaScript.

Converting a string to uppercase

Converting a string to uppercase is very simple.

Just use the built-in toUpperCase() method on the string that you want to transform.

The method will return a new string with all of the characters in the original string in uppercase.

Let's first start with a sample string:

	const string = "This is a string.";

const uppercasedString = string.toUpperCase();

console.log(uppercasedString);

	THIS IS A STRING.

Converting a string to lowercase

You can similarly do the reverse and lowercase strings by using the toLowerCase() method.

This method will take a string and convert all uppercase characters to lowercase and return the new string.

	const string = "THIS IS A STRING.";

const lowercasedString = string.toLowerCase();

console.log(lowercasedString);

	this is a string.

Conclusion

In this post, we learned how to convert a string to uppercase or lowercase in JavaScript.

Simply make use of the built-in toUpperCase() and toLowerCase() methods on strings.

Thanks for reading and happy coding!