var y_labels = parent.getElementsByClassName("dygraph-axis-label-y" + axis_num);
var ary = [];
for (var i = 0; i < y_labels.length; i++) {
var y_labels = parent.getElementsByClassName("dygraph-axis-label-y" + axis_num);
var ary = [];
for (var i = 0; i < y_labels.length; i++) {