Hi everyone! Does anyone know how to parse string to save function then save it as a html file in wysiwyg editor?

my code:
function MENU_FILE_SAVE_onclick() {

    filteredHTML = tbContentElement.FilterSourceCode (tbContentElement.DOM.body.innerHTML);

}

document.execCommand("saveas");//this will save the whole part of
editor, it can't use for it.

i want to save the string value (filteredHTML) in html file. Thank you. Example: <P>&nbsp;</P>