Explain This Seeming Inconsistency In JQuery/Javascript? (trailing Brackets Inconsistency On Reads)

So, in my example below, "InputDate'" is an input type=text, "DateColumn" is a TD within a table with a class of "DateColumn".

Read the value of a discreet texbox:

var inputVal = $('#InputDate').val();


Read the value of a div within a table....

This works:

$('#theTable .DateColumn').each(function() {
var rowDate = Date.parse($(this)[0].innerHTML);
});

This doesn't:

$('#theTable .DateColumn').each(function() {
var rowDate = Date.parse($(this)[0].innerHTML());
});

The difference is the "()" after innerHTML. This behavior seems syntactically inconsistent between how you read a value from a textbox and how you read it from a div. I'm ok with sometimes, depending on the type of control, having to read .val vs .innerHTML vs.whateverElseDependingOnTheTypeOfControl...but this example leads me to believe I now must also memorize whether I need trailing brackets or not on each property/method.

So for a person like me who is relatively new to jQuery/Javascript....I seem to have figured out this particular anomaly, in this instance, but is there a convention I am missing out on, or does a person have to literally have to memorize whether each method does or does not need brackets?