RCmerci/loop and closure

## loop and closure
for (var i = 0; i < divs.length; i++) {
  divs[i].addEventListener("click", function() {
    alert("divs #" + i + " was clicked.");
  }, false);
}

//这里的i被closure了，每次循环会被更新，而不是当时的值
	for (var i = 0; i < divs.length; i++) {
	divs[i].addEventListener("click", function() {
	alert("divs #" + i + " was clicked.");
	}, false);
	}

	//这里的i被closure了，每次循环会被更新，而不是当时的值