To set the border bottom properties in one declaration in JavaScript, use the borderBottom property. It allows you to set the border-bottom-width, border-bottom-style, and border-bottom-color.
Example
You can try to run the following code to learn how to set border bottom properties −
<!DOCTYPE html> <html> <head> <style> #box { border: 2px dashed blue; width: 120px; height: 120px; } </style> </head> <body> <button onclick="display()">Set border bottom color</button> <div id="box"> <p>Demo Text</p> <p>Demo Text</p> </div> <script> function display() { document.getElementById("box").style.borderBottom = "thin dashed #000000"; } </script> </body> </html>