difference between .touched & .dirty in angular
valid: This property returns true if the element’s contents are valid and false otherwise.
invalid: This property returns true if the element’s contents are invalid and false otherwise.
pristine: This property returns true if the element’s contents have not been changed.
dirty: This property returns true if the element’s contents have been changed.
untouched: This property returns true if the user has not visited the element.
touched: This property returns true if the user has visited the element.