+// For Dygraph.setDateSameTZ, below.
+Dygraph.dateSetters = {
+ ms: Date.prototype.setMilliseconds,
+ s: Date.prototype.setSeconds,
+ m: Date.prototype.setMinutes,
+ h: Date.prototype.setHours
+};
+
+/**
+ * This is like calling d.setSeconds(), d.setMinutes(), etc, except that it
+ * adjusts for time zone changes to keep the date/time parts consistent.
+ *
+ * For example, d.getSeconds(), d.getMinutes() and d.getHours() will all be
+ * the same before/after you call setDateSameTZ(d, {ms: 0}). The same is not
+ * true if you call d.setMilliseconds(0).
+ *
+ * @type {function(!Date, Object.<number>)}
+ */
+Dygraph.setDateSameTZ = function(d, parts) {
+ var tz = d.getTimezoneOffset();
+ for (var k in parts) {
+ if (!parts.hasOwnProperty(k)) continue;
+ var setter = Dygraph.dateSetters[k];
+ if (!setter) throw "Invalid setter: " + k;
+ setter.call(d, parts[k]);
+ if (d.getTimezoneOffset() != tz) {
+ d.setTime(d.getTime() + (tz - d.getTimezoneOffset()) * 60 * 1000);
+ }
+ }
+};