The substringData() method of the CharacterData interface returns a portion of the existing data, starting at the specified index and extending for a given number of characters afterwards.
substringData(offset, count)offsetThe index of the first character to include in the returned substring. 0 is the first character of the string.
countThe number of characters to return.
A string with the substring.
IndexSizeError DOMExceptionThrown if offset + count is larger than the length of the contained data.