May 28, 2022

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

By Krishnaa JavaScript Questions 0 Comments

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.

HTML & CSS

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">

<head>
  <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">
  <title>Document</title>
</head>

<body>

  <div class="container">    
    <button>Get</button>
    <h1>Result</h1>
  </div>

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

</html>

.container {        
    text-align: center;
}

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

Javascript

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;
  
});

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