+ // store original callbacks
+ var callBackTypes = ['drawCallback', 'highlightCallback', 'unhighlightCallback'];
+ for (var j = 0; j < dygraphs.length; j++) {
+ if (!prevCallbacks[j]) {
+ prevCallbacks[j] = {};
+ }
+ for (var k in callBackTypes) {
+ prevCallbacks[j][callBackTypes[k]] = dygraphs[j].getFunctionOption(callBackTypes[k]);
+ }
+ }
+