November 18, 2021

How to Detect Backspace Key in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to detect backspace key in javascript. In a standard keyboard layout, the backspace key is located in the top-right portion of the keyboard’s character keys section and has an arrow pointing to the left.

The backspace key deletes any character before the cursor’s current position and as a result, the cursor‘s position changes towards the left.

Whenever we press the backspace key or any other key on the keyboard, certain keyboard events are triggered. In the event handler function, the event object contains details about the keyboard event. The event object has a key property that can reveal which key has been pressed by the user.

To keep things simple, we are going to monitor keydown event and in the event handler function, we will verify whether the backspace key is pressed or not.

In the following example, we have an input field. As soon as the user presses the backspace key while typing in the input field, we will display a message 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, h1, and input).
The div element is just a wrapper for the rest of the elements. We are using style attribute with div element to center align the child elements.
The innerText for the h1 element is “Result”.
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">
    <title>Document</title>
</head>
<body>
      
    <div style="text-align: center">
        <input type="text" placeholder="Enter Text">
        <h1>Result</h1>
    </div>
    <script src="script.js"></script>
</body>
</html>

Javascript

We have selected the input element and h1 element using document.querySelector() method and stored them in the input and result variables respectively.
We have attached keydown event listener to the input element.
In the event handler function, we are using if statement and key property of the event object to verify whether the backspace key is pressed or not.
Depending upon the result of verification, we are updating innerText of the h1 element.

let input = document.querySelector("input");
let result = document.querySelector("h1");

input.addEventListener("keydown", (e) => {  
    
  if (e.key === "Backspace") {
    result.innerText = "Backspace Key Pressed";
  } else {
    result.innerText = "Backspace Key Not Pressed";
  }
});

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