To set the width of the right border in JavaScript, use the borderRightWidth property. Set the width of the right border using this property.
Example
You can try to run the following code to learn how to set the width of the right border with JavaScript.
<!DOCTYPE html>
<html>
<head>
<style>
#box {
border: thick solid blue;
width: 300px;
height: 300px;
}
</style>
</head>
<body>
<div id = "box">Demo Text</div>
<br><br>
<button type="button" onclick="display()">Change right border width</button>
<script>
function display() {
document.getElementById("box").style.borderRightWidth = "10px";
}
</script>
</body>
</html>