elmBtn.onclick = function(){BtnClickedFunction()} code example

Example 1: javascript onclick

var myElem = document.getElementByID('ElemID');
myElem.onclick = function() {
	//do stuff
}

Example 2: javascript onclick

// The element id (TheElementID) and var name (myElement) can be named anything.
var myElement = document.getElementByID('TheElementID');
myElement.onclick = function() {
	// Carry out a function here...
}