How to use toUpperCase() method in JavaScript?

Is it hard to capitalize string in JavaScript using toUpperCase(), or fully known as String.prototype.toUpperCase() method?

Well, this article will answer that question in a simple yet effective way.

So, if you want to know these significant details concerning JavaScript touppercase, keep reading!

This article will show you everything you need to know how to capitalize a string in JavaScript.

What is .toUpperCase() method in JavaScript?

The toUpperCase() method is a built-in JavaScript method that converts a string to uppercase letters.

It does not change the original string but returns a new string with all the characters in uppercase.

Syntax:

str.toUpperCase()

There’s no parameter.

Return value:

It returns a fresh new string with everything in uppercase letters.

What is the use of JavaScript .toUpperCase?

The .toUpperCase() method is used to convert a string to uppercase letters or ALL CAPS.

It can be useful in many situations, such as when you want to display text in all caps or when you want to compare strings in a case-insensitive manner.

For instance, you might use toUpperCase() to convert user input to uppercase before comparing it to a list of valid values to ensure that the comparison is case-insensitive.

How to capitalize a string in JavaScript using .toUpperCase() method?

The toUpperCase() method turns a normal string into ALL CAPS. But don’t worry, it doesn’t mess up your original text.

Instead, it creates a fresh new string with everything in uppercase letters.

Here are the examples of how to use the toUpperCase() method:

Example 1:

let samplestring = "Hi, Welcome to Itsourcecode!";
let result = samplestring.toUpperCase();✅
console.log(result);

Output:

HI, WELCOME TO ITSOURCECODE!

Example 2:

If you want to capitalize a specific parameter when calling a function, you can simply create the function and use .toUpperCase() on that parameter before returning it.

This way, the stated parameter will be in capitalized form whenever you call the function.

function func() {

	// our original string
	let str = "hi, welcome to itsourcecode!";

	// the string that we are going to convert to Upper Case
	let samplestring = str.toUpperCase();✅

	
	console.log(samplestring);
}

func();

Output:

HI, WELCOME TO ITSOURCECODE!

Example 3:

let str = ["it", "source", "code"];
 
let result = str.map(str => str.toUpperCase());✅
console.log(result);

As you can see, we created an array of str with elements “it,” “source,” and “code.” We used map() and toUpperCase() to convert each element to uppercase or ALL CAPS.

Output:

[ 'IT', 'SOURCE', 'CODE' ]

Example 4:

You can also use the toUpperCase() method on non-string values by setting its this to a value that is not a string.

Here’s an example:

const sample1 = String.prototype.toUpperCase.call({ toString() { return "itsourcecode"; }, });
const sample2 = String.prototype.toUpperCase.call(true);✅
console.log(sample1, sample2);

Output:

ITSOURCECODE TRUE

How to capitalize all letters in JavaScript?

To capitalize all letters in JavaScript, you can use the toUpperCase(), fully known as the String.prototype.toUpperCase() method when you need to capitalize or converts a string to uppercase letters in your JavaScript code.

This method returns a new string with all the characters of the original string converted to uppercase.

Conclusion

In conclusion, this article explains that using the toUpperCase() method in JavaScript, also known as String.prototype.toUpperCase(), is a straightforward way to capitalize a string.

The method converts a given string to uppercase letters without altering the original string and returns a new string with all characters in uppercase.

This article provides examples of how to use the toUpperCase() method in various scenarios, demonstrating its functionality with string.

We are hoping that this article provides you with enough information that helps you understand JavaScript touppercase.

You can also check out the following article:

• JavaScript array return
• JavaScript breakpoint
• Break from loop JavaScript

Thank you for reading itsourcecoders 😊.

Caren Bautista

Technical Writer at PIES IT Solution

Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.

Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel  · View all posts by Caren Bautista →