The HTMLSelectElement.checkValidity() method checks whether the element has any constraints and whether it satisfies them. If the element fails its constraints, the browser fires a cancelable invalid event at the element, and then returns false.
The HTMLSelectElement.setCustomValidity() method sets the custom validity message for the selection element to the specified message. Use the empty string to indicate that the element does not have a custom validity error.
The HTMLTableElement.createTFoot() method returns the <tfoot> element associated with the table, of type HTMLTableSectionElement. If there is no footer for this table, this methods creates it, then returns it.
The HTMLTableElement.createTHead()method returns the <thead> element association with the table, of type HTMLTableSectionElement. If there is no such element associated to the thable, this method creates it, then returns it.
The HTMLTableElement.deleteRow() method removes a row from the table. If the amount of rows to delete, specified by the parameter, is greater or equal to the number of available rows, or if it is negative and not equal to the special index -1, representing the last row of the table, the exception INDEX_SIZE_ERR is thrown.