Change the width of the outline of a <div> element, using the "thick" value:
document.getElementById("myDiv").style.outlineWidth = "thick";
<!DOCTYPE html> <html> <head> <style> #myDiv {//w ww . java2 s . co m border: 1px solid red; outline: thin solid green; } </style> </head> <body> <div id="myDiv">This is a div element.</div> <br> <button type="button" onclick="myFunction()">Change outline width</button> <script> function myFunction() { document.getElementById("myDiv").style.outlineWidth = "thick"; } </script> </body> </html>