You can prefill the textarea. If you want to prefill on multiline, you will have to add newline characters
The textarea can be disabled with the
readonly attribute indicate that you can't change the content. Compared with
disabled attribute, the
readonly attribute doesn't prevent clicking or selecting the element.
max-rows attribute to make it stop growing after a certain amount of lines.
To have a fixed size provide
max-rows with the same value.
It could be that your textarea is inside a hidden container, for example for a dialog or accordion or tabs. When it is hidden, the resizing is calculated based on the visible space of the text. Therefore, an Intersection Observer observes visibility changes of the textarea relative to the viewport, and resizes the textarea when a visibility change happens.
For old browsers like old Edge or IE11, a polyfill is required to be added on the application level for this to work. For most cases, the optimized default will suffice.
In the demo below you can see that the textarea is correctly calculated to 4 maximum rows, whereas without the observer, it would be on 2 rows and only resize on user input.