You can use addEventListener or onkeydown property to detect a used pressed backspace key or not in JavaScript. Where Backspace key keycode is 8 and key is “Backspace”.
Example of detect backspace key in JavaScript
HTML example code, popup alert box if the user presses the backspace key in the input box.
Using addEventListener
<!DOCTYPE html>
<html>
<body>
<input type="text" id="txtbox">
<script>
var input = document.getElementById('txtbox');
input.addEventListener('keydown', function(event) {
const key = event.key;
if (key === "Backspace") {
alert(key);
}
});
</script>
</body>
</html>Using .onkeydown
More recent and much cleaner: use event.key
<!DOCTYPE html>
<html>
<body>
<input type="text" id="txtbox">
<script>
var input = document.getElementById('txtbox');
input.onkeydown = function() {
const key = event.key;
if (key === "Backspace") {
alert(key);
}
};
</script>
</body>
</html>Output:
Do comment if you have any doubts or suggestions on this JS key topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version