while layer.onclick set to null in the handler, but the handler still execute.

[borenXue]

while my code is below, the handler will execute multiple times.
But In fact, I only need to execute it once

document.addEventListener('DOMContentLoaded', function() {

	document.body.onclick = function () {
		// do something
		document.body.onclick = null
	}

	FastClick.attach(document.body);

}, false);