JavaScript program to get a variable to count up/down on keyboard press.

JavascriptWeb DevelopmentObject Oriented Programming

Following is the code to increment or decrement a variable on keyboard up/down press in JavaScript −


 Live Demo

<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   .result {
      font-size: 20px;
      font-weight: 500;
<h1>Changing variable value on keyboad up/down keypress</h1>
<div style="color: green;" class="result"></div&g;
Press up or down arrow key to increment/decrement variable
   let dayVal = document.querySelector(".day");
   let resEle = document.querySelector(".result");
   let a = 0;
   resEle.innerHTML = a;
   document.body.addEventListener("keydown", (event) => {
      if (event.keyCode === 38) {
         resEle.innerHTML = ++a;
      else if (event.keyCode === 40) {
         resEle.innerHTML = --a;


The above code will produce the following output −

On pressing up arrow key a couple of times −

On pressing down arrow key a few times −

Updated on 17-Jul-2020 08:50:29