June 20, 2022

How to Trim and Lowercase in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to trim and lowercase in javascript. Trimming means removing any extra unwanted space at the beginning and at the end of the string. For a newbie developer, it can be a bit tricky to trim a string and then convert it into a lowercase.

There are numerous ways to trim and convert a string to a lowercase. But for the sake of simplicity, we will use trim() method and toLowerCase() method. The trim() method removes any extra space at the beginning and at the end of a string. The toLowerCase() method will convert the string to lowercase.

In the following example, we have one global variable that holds a string. Upon click of a button, we will trim and convert the string to 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 “Trim” 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>Trim</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 btnTrim and output variables respectively.
We have a global variable myString which holds a text as its value.
We are displaying myString in the h1 element using innerText property.
We have attached a click event listener to the button element.
In the event handler function, we are calling trim() method to remove any extra space at the beginning and at the end of the string. This trim() method will return a new string.
We are calling toLowerCase() method to convert the trimmed string to lowercase.
We are storing the final string in the result variable.
We are displaying the result in the h1 element using the innerText property.

let btnTrim = document.querySelector("button");
let output = document.querySelector("h1");

let myString = ` MBA stands for Master of Business Administration   `;
output.innerText =  myString;
 
btnTrim.addEventListener("click", () => {  
  let result = myString.trim().toLowerCase();
  output.innerText = result;
});

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