(PHP 5, PHP 7)
DOMCharacterData::insertData — Insert a string at the specified 16-bit unit offset
$offset
   , string $data
   )
   Inserts string data at position offset.
  
offsetThe character offset at which to insert.
dataThe string to insert.
No value is returned.
DOM_INDEX_SIZE_ERR
       Raised if offset is negative or greater than the
       number of 16-bit units in data.