Can't update textarea with javascript after writing to it manually

I had this same problem. When HTML is parsing to DOM object, content of textarea is innetHTML of <textarea>

<textarea cols="10" rows="10">Content of textarea</textarea>

Values document.getElementByTagName('textarea').innerHTML and document.getElementByTagName('textarea').value returns this same value Content of textarea

But after loading DOM object, changing innerHTML value doesn't change content of textarea box. A solution to change it is modifying value field.

document.getElementByTagName('textarea').value="New content of textarea";

or in jquery

$("textarea").val("New content of textarea");

.value and .innerHTML seemed to fix the problem