How can i know from Dom of object if it supports javascript?

Sir,

i Have a login page,with username & pwd fields.
Am entering data into above fields using Javascript executor & click "Naeste" button.

Script used to enter username & password:

WrapsDriver wd = (WrapsDriver) Element;//Element here is a WebElement where object is collected via xpath
JavascriptExecutor driver = (JavascriptExecutor)wd.getWrappedDriver();
driver.executeScript("arguments[0].setAttribute(arguments[1],arguments[2])",
Element, "placeholder", “username”);//same code for pwd


[b:1z2b2iue]Issue:[/b:1z2b2iue] When i click "naeste" button, application throws error that "username & pwd are not entered".But i can see that both username & pwd [valid ones] are entered successfully.But application is not recognizing that username & pwd is entered.

[b:1z2b2iue]Query:Can i know from DOM structure of a object if its Javascript enabled ?[/b:1z2b2iue]

References: Have cross checked :chromebrowser is javascript enabled.
:Found no references on net which addresses this.