how to write event handler for multiple buttons js code example

Example: multiple event with javascript

/* get the button id "tg" which is used for toggling.Then on click few 
elements with classname "adv" will disappear and at the same time few elements 
with classname "btnpro" will increase in width to 80px*. Upon second click  
elements with "adv" will appear again and the button width changes to 60px*/

document.getElementById("tg").onclick = function ()
{
  my_fun1();
  my_fun2();
}

function my_fun1()
{
  var x = document.getElementsByClassName("adv")
    for(var i=0; i