How to make ie9.0 browser support Getelementsbyclassname

/**             * node is the search starting point for the DOM tree, and ClassName is the name of the class that needs to be searched.             * If the appropriate getelementsbyclassname is already present on the incoming node, return to the corresponding node list             * If this method is not supported, the new function will traverse all tags to find the corresponding class name element             *                         */ function getelementsbyclassname (node, Classname) {                if (node.getelementsbyclassname) {                    //Use new method                    return Node.getelementsbyclassname (Classname);                } else{                    var results=new Array ();                    var elems=node.getelementsbytagname ("*");                    for (var i=0; i<elems.length;i++) {                        if (Elems[i].classname.indexof (className)!=-1) {                            results[ Results.length]=elems[i];                        }                        return results;}}            }

How to make ie9.0 browser support Getelementsbyclassname