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JavaScript program to get a variable to count up/down on keyboard press.
Following is the code to increment or decrement a variable on keyboard up/down press in JavaScript −
Example
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>>Document</title> <style> body { font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif; } .result { font-size: 20px; font-weight: 500; } </style> </head> <body> <h1>Changing variable value on keyboad up/down keypress</h1> <div style="color: green;" class="result"></div&g; <h3> Press up or down arrow key to increment/decrement variable </h3> <script> 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; } }); </script> </body> </html>
Output
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 −
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