Javascript string toUpperCase()

Javascript toUpperCase()
In this article, we will take a look at how to convert a string to upper case using toUpperCase() method in javascript. This article will also cover how to convert first letter of a string to upper case.

toUpperCase()
toUpperCase() method is called on a string object and returns a new string with all the characters of the calling string converted to upper case. Example,

let str = 'fox jumps';
let str_upper = str.toUpperCase();
console.log('Actual string: ' + str);
console.log('String in upper case: ' + str.toUpperCase());

This prints

toUpperCase() converts only alphabets to upper case. Numbers and special characters remain unaffected. Example,

let str = 'fox jumps @1& wall';
let str_upper = str.toUpperCase();
console.log('Actual string: ' + str);
console.log('String in upper case: ' + str.toUpperCase());

This prints

Also, remember that toUpperCase() returns a new string, original string remains unchanged as can be seen from above examples.

Following example demonstrates that both the strings are different. It compares both the string using == operator.

let str = 'fox jumps'; 
let str_upper = str.toUpperCase(); 
console.log('Strings are same: ' + (str == str_upper));

This prints

Convert first letter uppercase
To get the first letter of a string, use javascript string charAt() method.
charAt() takes a number as argument and returns the character at that index. First character is placed at index 0.
So, passing 0 as argument to charAt() returns the first character. Note that the return type of charAt() is a string.
Therefore, if we invoke charAt() followed by toUpperCase(), then first letter will be converted to upper case.

Next, append the remaining string to this capitalized first character. To get the remaining string, use any of javascript substring methods such as splice() method.
splice() method accepts an integer argument and returns the string with characters from index equal to the argument till the end of string. So, 'abcde'.splice(1) will return ‘bcde’.

Program example to make the first letter of a string to upper case is given below

let str = 'fox jumps'; 
// get first character
let firstChar = str.charAt(0);
// get string without first character
let remaining = str.splice(1); 
console.log('String with first character upper case: ' + firstChar.toUpperCase()+remaining);

Output is

Hope the article was useful.