this

explains this in javascript

HTML

<div id="mydiv">
         <div><h1>DIV 1</h1></div>
         <div><h1>DIV 2</h1></div>
         <div><h1>DIeeeV 3</h1></div>
         <div><h1>DIV 4</h1></div>
         <div><h1>DIV 5</h1></div>
         <div><h1>DIV 6</h1></div>
      </div>

JavaScript

var divs = document.getElementById("mydiv").getElementsByTagName("div");

      for(var i =0; i < divs.length ; i++){
         divs[i].onclick = function (){
              if(this.style.color == "green"){
                   this.style.color = "red";
              }else{
                   this.backgroundColor = "green";
              }
         }
      }