Override Function JS keeping Original

//https://jsfiddle.net/9n9y2soc/1/
//https://jsfiddle.net/bz5yhgza/

//pre esistent function
function deleteCob(id){
    console.log("deleteCob - id:"+id)
}

//get the function
var common_deleteCob = typeof deleteCob !== "undefined" ? deleteCob : function() {
};

//override it
deleteCob = function(idCoob){
    myFunction();
    common_deleteCob(idCoob);
}

//our new function
function myFunction(){
    console.log("myFunction");
}

///then call it
deleteCob(234);