Ran into this problem today, posting in case someone else has the same issue.

var execBtn = document.createElement('input');
execBtn.setAttribute("type", "button");
execBtn.setAttribute("id", "execBtn");
execBtn.setAttribute("value", "Execute");
execBtn.setAttribute("onclick", "runCommand();");

Turns out to get IE to run an onclick on a dynamically generated element, we can't use setAttribute. Instead, we need to set the onclick property on the object with an anonymous function wrapping the code we want to run.

execBtn.onclick = function() { runCommand() };

BAD IDEAS:

You can do

execBtn.setAttribute("onclick", function() { runCommand() });

but it will break in IE in non-standards mode according to @scunliffe.

You can't do this at all

execBtn.setAttribute("onclick", runCommand() );

because it executes immediately, and sets the result of runCommand() to be the onClick attribute value, nor can you do

execBtn.setAttribute("onclick", runCommand);