Check if SharePoint page is in edit mode in Javascript

If embedded javascript code needs to check if the sharepoint page is in edit mode, the script below can be used.

var inDesignMode = document.forms[MSOWebPartPageFormName].MSOLayout_InDesignMode.value;

if (inDesignMode == "1")
{
    // page is in edit mode
}
else
{
    // page is in browse mode
}

Copied from http://sharepoint.stackexchange.com/questions/12792/how-do-i-know-if-the-page-is-in-edit-mode-from-javascript