Why Event Listener Not Changing? : 
**HTML**

   < div id="q">< /div>

**Style**

    #q  {
    width:40px;
    height:40px;
    background-color:blue;
     }

**Javascript**
   
      window.onload = function () {
    var a = document.getElementById("q");
    var b = 1;
    function tri() {
        a.style.width = "100px"; 
    b++
        if(b == 3) {
         b--
    }
        return b; }    

    function un() {
        a.style.width = "40px"    
        if(b == 2) {
        b--
      }
    };
    if(b == 1) {
    a.addEventListener("click",tri);
        };
        
      if(b == 2) {
            a.addEventListener("click",un)
            
        };
    };

I Don't Know Why But My Code Is Not Working 
Is it Possible To Add To EVENT Listeners In one Element If Yes Then Please Explain How I Tried Lot But It's Not Working