function addLoadEvent(func){

            var oldonLoad = window.onload;

            if(typeof window.onload != 'function'){

                window.onload = func;

            }else{

                window.onload = function(){

                    oldonLoad();

                    func();

                }

            }

        }

        function c1(){

            console.log(1)

        }

        function c2(){

            console.log(2)

        }

        function c3(){

            console.log(3)

        }

        addLoadEvent(c3)

        addLoadEvent(c1)

        addLoadEvent(c2)