Example 1: Convert First letter to UpperCase
// program to convert first letter of a string to uppercase
function capitalizeFirstLetter(str) {
// converting first letter to uppercase
const capitalized = str.charAt(0).toUpperCase() + str.slice(1);
return capitalized;
}
// take input
const string = prompt('Enter a string: ');
const result = capitalizeFirstLetter(string);
console.log(result);
Output
Enter a string: javaScript JavaScript
In the above program, the user is prompted to enter a string and that string is passed into the capitalizeFirstLetter() function.
- The string's first character is extracted using charAt() method. Here,
str.charAt(0);gives j. - The
toUpperCase()method converts the string to uppercase. Here,str.charAt(0).toUpperCase();gives J. - The
slice()method returns the rest of the string.
Here,str.slice(1);gives avaScript. - These two values are concatenated using the
+operator.
Note: You can also extract the first character of a string using an array accessing property: str[0].
str.str[0]; // j
Example 2: Convert First letter to UpperCase using Regex
// program to convert first letter of a string to uppercase
function capitalizeFirstLetter(str) {
// converting first letter to uppercase
const capitalized = str.replace(/^./, str[0].toUpperCase());
return capitalized;
}
// take input
const string = prompt('Enter a string: ');
const result = capitalizeFirstLetter(string);
console.log(result);
Output
Enter a string: javaScript JavaScript
In the above program, the regular expression(regex) is used to convert the first letter of a string to uppercase.
- The regex pattern is
/^./matches the first character of a string. - The
toUpperCase()method converts the string to uppercase.
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