Javascript- Do something on date change in Datetime field- Newform.aspx

I am doing changes in newform.aspx using javascript.. I need to do something when there is change in date field("Publishing Date"). It is a datetime picker..

I tried like...

$(document).ready(function()

{

getTagFromIdentifierAndTitle("input","DateTimeFieldDate","Publishing Date").onchange = function() {ChangeEvent1()};

});

function ChangeEvent1()
{

//do something

}

function getTagFromIdentifierAndTitle(tagName, identifier, title) {
 var len = identifier.length;
 var tags = document.getElementsByTagName(tagName);
 for (var i=0; i < tags.length; i++) {
 var tempString = tags[i].id;
 if (tags[i].title == title && (identifier == "" || tempString.indexOf(identifier) == tempString.length - len)) {
 return tags[i];
 }
 }
 return null;
}

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please help