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toUpperCase() in JavaScript – How to Convert String to Uppercase

Whenever you use toUpperCase() on a string, the method does the following:

  1. It converts its calling string to uppercase.
  2. It returns the new version of the calling string—without changing the original string.
note

A calling string is a string on which you used toUpperCase(). So, in "Hello, World!".toUpperCase(), "Hello, World!" is the calling string.

Syntax of the toUpperCase() Method

Here is toUpperCase()'s syntax:

callingString.toUpperCase();

The snippet above shows that toUpperCase() does not accept any argument.

Example 1: Convert CodeSweetly to Uppercase

"CodeSweetly".toUpperCase();

// The invocation above will return: "CODESWEETLY"

Try it on StackBlitz

Example 2: Convert a JavaScript String to Uppercase

"friday, my friend, was born on friday".toUpperCase();

// The invocation above will return: "FRIDAY, MY FRIEND, WAS BORN ON FRIDAY"

Try it on StackBlitz

tip

To convert a JavaScript string to lowercase, use toLowerCase().

Overview

toUpperCase() returns the uppercase version of its calling string.

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