Difference between Element.value and Element.getAttribute("value")

The difference is that element.value is real time and if a user changes let's say, a textbox input, it will reflect that, and show you the new value.

While getAttribute('value') will still show the original value="whateverWasHere" value.

jsFiddle DEMO

.value does not map to any attribute.

.defaultValue maps to the "value" attribute. So when you say elem.getAttribute("value") that's the same as elem.defaultValue.

Additionally, .defaultValue reflects .value when the input is untouched (dirty value flag is false). After the input's value is changed by user interaction, this mapping stops. While the input is untouched, you can change .defaultValue (and thus .setAttribute("value")) and see it change .value as well. Not that this is practically useful but interesting piece of trivia nevertheless.