Javascript: How to make first letter of a string uppercase

Strings are JavaScript’s data type used to represent the textual data and are most commonly used. Many people encounter a general requirement to Capitalize the first letter of a String. This article will discuss different ways to make the first letter uppercase using examples.

Javascript’s toUpperCase() will return the calling string converted to uppercase. If the calling value is not a string, it will convert it.

We will be using toUpperCase() to convert the first letter to upper case.

Table of Contents:-

Capitalize first letter of a string uppercase using slice() or substring()

Javascript’s slice() method returns a new String object, a portion of the calling string based on indexes passed as arguments. 

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Javascript’s substring() method returns a subset of the string between the start and end indexes or to the end of the string. 

See the differences between substring() and slice()

Example:-

Capitalize the first letter of string “javascript is a versatile language”

Code:-

function firstLetterCapitalize(_string) {
    return _string.charAt(0).toUpperCase() + _string.slice(1);
  }

OR

function firstLetterCapitalize(_string) {
    return _string.charAt(0).toUpperCase() + _string.substring(1);
  }

Usage:-

let dummyString = 'javascript is a versatile language';
console.log(firstLetterCapitalize(dummyString));

Output:-

Javascript is a versatile language

Explanation:-

  • Step1: The argument string passed in function firstLetterCapitalize() is the string to be processed. Hence, the first character of this string is capitalised by _string.charAt(0).toUpperCase().
  • Step2: To the new string formed by _string.charAt(0).toUpperCase() rest of the string is added which is other than the first character and is obtained by either _string.substring(1) or _string.slice(1).

Capitalize first letter of a string uppercase using regExp

Regular Expression is used to match a particular text/string with a pattern.

Example:-

Capitalize the first letter of string “javascript is a versatile language”

Code:-

function firstLetterCapitalize(_string) {
    return _string.replace(/^./, _string[0].toUpperCase());
  }

Usage:-

let dummyString = 'javascript is a versatile language';
console.log(firstLetterCapitalize(dummyString));

Output:-

Javascript is a versatile language

Explanation:-

The above code uses the replace() method to get the string’s first character and replace it with its uppercase.

  • / and / mark the beginning and the end of the pattern.
  • ^. specifies to match single character at the beginning of the string.

Capitalize first letter of a string uppercase using join()

Javascript’s join() method creates and returns a string after concatenating all elements of an array.

Example:-

Capitalize the first letter of string “javascript is a versatile language”

Code:-

function firstLetterCapitalize([ firstletter, ...remainingString ]) {
    return [ firstletter.toUpperCase(), ...remainingString ].join('');
  }

Usage:-

let dummyString = 'javascript is a versatile language';
console.log(firstLetterCapitalize(dummyString));

Output:-

Javascript is a versatile language

Explanation:-

In the above code we are splitting the string into an array, After that we covert first array element to uppercase and finally join both the elements of array by join() method.

Read More:

I hope this article helped you to convert the first letter of a string into uppercase. Good Luck!!!

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