Convert first letters of a string to uppercase in JavaScript

In this tutorial, we will learn how to convert the first letters of a string to uppercase in JavaScript.

Variables used in code

• str – string

const str = "This is a Tutorial in CodeSpeedy"

Method 1

We’ll divide the string into an array of words, capitalize the first letter of each word, and then join the array of words back together.

Inbuilt Methods used 

• split() – split a string to array
• join() – join array elements to string
• toUpperCase() – convert string to uppercase

let wordArray  = str.split(" ")
for(let i = 0; i < wordArray.length; i++) {
    if(wordArray[i] !== ""){
        wordArray[i] = wordArray[i][0].toUpperCase() + wordArray[i].slice(1,) 
    }
}
let uppercaseString = wordArray.join(" ")
console.log(uppercaseString)

Method 2

Instead of converting a string to an array and then back to a string. This method works directly with string.

Inbuilt Methods used 

• charAt() – get the char at required position
• slice() – slice a string
• indexOf() – find the index of a substring
• toUpperCase() – convert string to uppercase

function FirstLettersToUppercase(str) {
    if (str != "") {
        str = str.charAt(0).toUpperCase() + str.slice(1)
    }
    let i = 0
    while(i !== -1 & i < str.length) {
        let index = str.indexOf(" ",i)
        if(index !== -1 & str.charAt(index+1) !== " ") {
    	    str = str.slice(0,index+1) + str.charAt(index+1).toUpperCase() + str.slice(index+2)
            i = index + 1
        }
        else if(index === -1){
    	    i = index 
        }
        else{
    	    i = index + 1
        }
    }
    return str
}

let uppercaseString = FirstLettersToUppercase(str)
console.log(uppercaseString)

Output

"This Is A Tutorial In CodeSpeedy"

Also read: Convert string to array in JavaScript