onChanged property
Called when the user initiates a change to the MongolTextField's value: when they have inserted or deleted text.
This callback doesn't run when the MongolTextField's text is changed programmatically, via the MongolTextField's controller. Typically it isn't necessary to be notified of such changes, since they're initiated by the app itself.
To be notified of all changes to the MongolTextField's text, cursor, and selection, one can add a listener to its controller with TextEditingController.addListener.
Handling emojis and other complex characters
It's important to always use characters when dealing with user input text that may contain complex characters. This will ensure that extended grapheme clusters and surrogate pairs are treated as single characters, as they appear to the user.
For example, when finding the length of some user input, use
string.characters.length. Do NOT use string.length or even
string.runes.length. For the complex character "👨👩👦", this
appears to the user as a single character, and string.characters.length
intuitively returns 1. On the other hand, string.length returns 8, and
string.runes.length returns 5!
See also:
- inputFormatters, which are called before onChanged runs and can validate and change ("format") the input value.
- onEditingComplete, onSubmitted: which are more specialized input change notifications.
Implementation
final ValueChanged<String>? onChanged;