best way to write jQuery's replaceWith() in natural JavaScript
var image = document.getElementById('imagefiles'), parent = image.parentNode,
tempDiv = document.createElement('div');
tempDiv.innerHTML = "<input type='file' name='imagefiles' id='imagefiles' />"
var input = tempDiv.childNodes[0];
parent.replaceChild(input, image);
DEMO
EDIT as per am not i am:
var image = document.getElementById('imagefiles'), parent = image.parentNode,
input = document.createElement('input');
input.id = input.name = "imagefiles";
input.type = 'file';
parent.replaceChild(input, image);