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How to uppercase a string in JavaScript?

Tim Mouskhelichvili
Tim Mouskhelichvili
2 minutes to read

In JavaScript, to make a string uppercase, the easiest way to do it is by using the toUpperCase() built-in function.

This function is easy to master (even for a beginner), and you will become a pro of using it by the end of this article.

I will also be providing some valuables use cases that you may encounter while developing in JavaScript.

How to uppercase a string in JavaScript?

Definition

The toUpperCase() function is used to uppercase a string.

Here is the toUpperCase() function syntax.

yourString.toUpperCase();

Here is an example of how you would call that function.

javascriptconst str = "This is a very long string!";

// This will return => "THIS IS A VERY LONG STRING!"
console.log(str.toUpperCase());

In that case, it will return: "THIS IS A VERY LONG STRING!".

1. Parameters

The toUpperCase() function does not accept any parameters.

2. Return Value

The toUpperCase() function returns the string converted to uppercase.

Browser Support

The toUpperCase() function works on all browsers. 🥳

BrowserSupport
ChromeYES ✅
FirefoxYES ✅
OperaYES ✅
SafariYES ✅
EdgeYES ✅
Internet ExplorerYES ✅

How to uppercase the first letter?

You have a few options to uppercase the first letter of a string.

1. Using the charAt() with the slice() function.

In order to uppercase the first letter of a string you can use the chatAt() and thetoUpperCase() functions and concatenate the result to the slice() function.

javascriptconst str = "this is a very long string!";

// This will return => "This is a very long string!"
console.log(str.charAt(0).toUpperCase() + str.slice(1));

In that case, it will return: "This is a very long string!".

2. Using the replace() function.

Also, you can use the replace() function to uppercase the first letter of a string.

typescriptconst str = "this is a very long string!";

// This will return => "This is a very long string!"
console.log(str.replace(/./, c => c.toUpperCase()));

In that case, it will return: "This is a very long string!".

How to uppercase the first letter of each word?

You can use a regex to uppercase the first letter of each word.

typescriptconst str = "This Is A Very Long String!";

// This will return => "This Is A Very Long String!"
console.log(str.replace(/(^|\s)\S/g, (letter) => letter.toUpperCase()));

In that case, it will return: "This Is A Very Long String!".

You can learn more by reading my article on how to uppercase the first letter.

Final Thoughts

As you can see the toUpperCase() is pretty straight and forward and not difficult to master.

Now that you are a pro of this function please share this article with your fellow coders.

JavaScript toUpperCase

Thank you for reading.

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