How Do I Make the First Letter of a String Lowercase in Javascript

In this tutorial, you will learn how do I make the first letter of a string lowercase in javascript. The first character in a string could be in uppercase. From a developer perspective, it can be a bit tricky to make the first letter of a string lowercase.

There are numerous ways to make the first letter of a string lowercase. But for the sake of simplicity, we will use toLowerCase() method, substr() method and charAt() method. The toLowerCase() method method will simply convert the string to a lowercase string and return a new string. The substr() method returns a substring. It takes 2 parameters, start position for extraction and number of characters to extract.

A string consists of multiple characters and these characters in a string have a 0-based index. To get a particular character in a string, we can pass its index to the charAt() method.

In the following example, we have one global variable that holds a string. Upon click of a button, we will make the first letter of a string lowercase and display the result on the screen.  Please have a look over the code example and the steps given below.


  • We have 3 elements in the HTML file (div, button, and h1). The div element is just a wrapper for the rest of the elements.
  • The innerText for the button element is “Get” and for the h1 element, it is “Result”.
  • We have done some basic styling using CSS and added the link to our style.css stylesheet inside the head element.
  • We have also included our javascript file script.js with a script tag at the bottom.
<!DOCTYPE html>
<html lang="en">

  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">


  <div class="container">    

  <script src="script.js"></script>

.container {        
    text-align: center;

button {
  margin-top: 10px;
  padding: 10px 20px;


  • We have selected the button element and h1 element using the document.querySelector() method and stored them in btnGet and output variables respectively.
  • We have attached a click event listener to the button element.
  • We have a global variable myString which holds a string as its value.
  • We are displaying the original string in the h1 element using the innerText property.
  • In the event handler function, we are calling the charAt() method and passing 0 as a parameter to get the first letter. We are calling toLowerCase() to convert the first letter into a lowercase letter and storing that in the first variable.
  • We are calling the substr() method and passing 1 as parameter to get the rest of the string.  The rest of the string is stored in the remaining variable.
  • We are concatenating values of two variables, first and remaining using addition (+) operator. The final string is stored in the result variable.
  • We are displaying the result in the h1 element using the innerText property.
let btnGet = document.querySelector("button");
let output = document.querySelector("h1");

let myString = "Keep moving and don't stop";
output.innerText = myString;
btnGet.addEventListener("click", () => {

  let first = myString.charAt(0).toLowerCase();
  let remaining = myString.substr(1);
  let result = first + remaining;
  output.innerText = result;