replace onmousedown with javascript -

Do anyone know how I can change the onoside value with javascript?

For example:

  & lt; Input style = "display: inline" type = "text" autocomplete = "off" name = "endDateAdd" id = "endDate" onkeydown = "return (case, incident)" onmousedown = "InitCal (this, '{$ minCal } ', Tap) "value =" {$ endDate} "& gt;   
 For the above code, I want to change the "toMousedown =" initCal (this, '' , Blank) " Does anyone know how to do this in JavaScript? 
 

Assume that you are talking about changing event handlers when the element is already on the page Only happens:

  document.getElementById ('endDate'). Onmousedown = function () {initCal (this, '', blank); };