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Mayu Hayakawa
Mayu Hayakawa

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How capitalize the first letter of each word in a string?

Hi! I'm Mayu.
In this post, I introduce how to change letter's case in JavaScript.

Now, here is a sentence about me.

i LOVE JaVa SpaRRoW!

How do you feel when you read this sentence?
A little it?
(By the way, recently I realized this is an expression of interesting intonation. I didn't know this before I started learning English, so I am happy about this realization!)

So, let's make function to the sentence to be more readable :)✨

function changeLetter(text) {
    let word = text.split(" ");
    let arr =[];
    for(let i= 0; i < word.length; i++){
        arr.push(word[i].charAt(0).toUpperCase() + word[i].substring(1).toLowerCase());
    return arr.join(" ");

console.log(changeLetter('i LOVE JaVa SpaRRoW!'));
// I Love Java Sparrow!
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1. Set space as separater and split sentences into words.

  • split() to split sentence with spaces(" ").

2. Add elements that capitalized only the first letter to the array.

  • use loop because each texts have more than 2 words.
  • charAt() method that returns new string
  • toUpperCase() method returns the calling string value converted to uppercase
  • substring() method that returns the part of the string
  • toLowerCase() method returns the calling string value converted to lowercase
  • push() method that adds elements to the end of an array

3. Return to a sentence with a space between words.

  • join() method creates and returns a new string by concatenating all of the elements in an array, separated by commas or a specified separator string.

reference: mdn

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