How to disable arrow key in textarea using JavaScript ? - GeeksforGeeks

31 Oct, 2019
Given an HTML element containing the <textarea> element and the task is to disable scrolling through arrow keys with the help of JavaScript.
Approach 1:
Add an event listener onkeydown on the window.
If the event happens then check if the keys are arrow or not.
If arrow key is pressed then prevent its default behaviour.
Example: This example implements the above approach.
<!DOCTYPE HTML> <html>   <head>     <title>         How to disable arrow key in        textarea using JavaScript ?    </title>          <style>        #t {            height: 100px;            width: 300px;            background: green;            color: white;        }    </style></head>   <body style = "text-align:center;">           <h1 style = "color:green;" >         GeeksforGeeks     </h1>          <p id = "GFG_UP" style =        "font-size: 15px; font-weight: bold;">    </p>          <textarea id = "t">        JavaScript was once upon a time used        only in client side(browser), but node        js (execution engine/run time/web         server) have made possible to run        javascript on server side. JavaScript        has stormed the web technology and        nowadays small software ventures to        fortune 500, all are using node js        for web apps.     </textarea>    <br>          <button onclick = "gfg_Run()">         click here    </button>          <p id = "GFG_DOWN" style = "color:green;        font-size: 20px; font-weight: bold;">    </p>          <script>        var el_up = document.getElementById("GFG_UP");        var el_down = document.getElementById("GFG_DOWN");                  el_up.innerHTML = "Click on the button to disable"                    + " scrolling through arrow keys.";                  function gfg_Run() {            window.addEventListener("keydown", function(e) {                if([32, 37, 38, 39, 40].indexOf(e.keyCode) > -1){                    e.preventDefault();                }            }, false);                          el_down.innerHTML =                 "Scrolling from arrow keys is disabled.";        }             </script> </body>   </html>
Output:
Before clicking on the button:
After clicking on the button:
Approach 2:
This example is quite similar to the previous one. It also maintains an array of which keys are pressed and when keyup event happens it removes them from array.
Add a event listener onkeydown on the window.
If the event happens then check if the keys are arrow or not.
If arrow key is pressed then prevent its default behaviour.
Example: This example implements the above approach.
<!DOCTYPE HTML> <html>   <head>     <title>         How to disable arrow key in        textarea using JavaScript ?    </title>          <style>        #t {            height: 100px;            width: 300px;            background: green;            color: white;        }    </style></head>   <body style = "text-align:center;">           <h1 style = "color:green;" >         GeeksforGeeks     </h1>          <p id = "GFG_UP" style =        "font-size: 15px; font-weight: bold;">    </p>          <textarea id = "t">        JavaScript was once upon a time used        only in client side(browser), but node        js (execution engine/run time/web         server) have made possible to run        javascript on server side. JavaScript        has stormed the web technology and        nowadays small software ventures to        fortune 500, all are using node js        for web apps.     </textarea>    <br>          <button onclick = "gfg_Run()">         click here    </button>          <p id = "GFG_DOWN" style = "color:green;        font-size: 20px; font-weight: bold;">    </p>          <script>        var el_up = document.getElementById("GFG_UP");        var el_down = document.getElementById("GFG_DOWN");                  el_up.innerHTML = "Click on the button to disable"                + " scrolling through arrow keys.";                  function gfg_Run() {            var key = {};            window.addEventListener("keydown", function(e) {                key[e.keyCode] = true;                switch(e.keyCode){                    case 37: case 39: case 38: case 40:                    case 32: e.preventDefault(); break;                     default: break;                }            }, false);                          window.addEventListener('keyup', function(e){                key[e.keyCode] = false;            }, false);                          el_down.innerHTML =                 "Scrolling from arrow keys is disabled.";        }             </script> </body>   </html>
Output:
Before clicking on the button:
After clicking on the button:
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