contenteditable does not apply to empty elements, so you may need to insert a character without a break in the empty elements you want to edit
non-expanding space " "will act as a symbol if left alone,
while a space " "will be considered only a symbol if it is placed after another symbol
<div>" "</div>----------------> innerHTML = undefined
<div>" "</div>-------->innerHTML = 
html
, " ", " "
var nbsp = " ",
div = document.getElementById('id');
div.innerHTML = nbsp
jquery
var div = $('div#id')
div.html(nbsp1)