http://www.whatwg.org/specs/web-apps/current-work/multipage/the-input-element.html#the-input-element <http://www.whatwg.org/specs/web-apps/current-work/multipage/the-input-element.html#the-input-element>
attribute float valueAsNumber <http://www.whatwg.org/specs/web-apps/current-work/multipage/common-input-element-attributes.html#dom-input-valueasnumber>;
valueAsNumber is defined as float, IEEE754 single precision number. It should be double because number values for date and time types are milliseconds from UNIX epoch. As of today, milliseconds from UNIX epoch is about 1,264,492,163,000. The float type can't represent this value precisely. If we do the following with float valueAsNumber, the input value loses the data. input.type = "datetime"; input.value = "2010-01-26T08:00Z"; var num = input.valueAsNumber; input.valueAsNumber = num; -- TAMURA Kent Software Engineer, Google
