how to get the value of button clicked in javascript code example

Example 1: javascript onclick get event

<div onclick="doSomething(event,this)"></div>
<script>
     function doSomething(e,el){
         e = e || window.event;
         console.log(e); //will be the event
         console.log(el); //we be the dom element 
     }
</script>

Example 2: javascript click button by id

var button = document.getElementById("button");
button.click();