JavaScript - Uncaught SyntaxError: Unexpected token =

function addTransitionEnd(){

    var className = document.getElementsByClassName("djslider-in");

    for(var i = 0; i < className.length; i++){

         className[i].addEventListener("transitionend", function(){

             this.style.animation = "zoom 2s infinite";

         });

    }

};

window.addEventListener('load', function(event) {

    function addTransitionEnd(){

        var className = document.getElementsByClassName('djslider-in');

        for(var i = 0; i < className.length; i++){

            className[i].addEventListener("transitionend", function(){

                this.style.animation = "zoom 2s infinite";

                this.style.WebkitAnimation = "zoom 2s infinite";

            });

            className[i].addEventListener("webkitTransitionEnd", function(){

                this.style.animation = "zoom 2s infinite";

                this.style.WebkitAnimation = "zoom 2s infinite";

            });

        }

    }

    addTransitionEnd();

});