Stretchy is a good script for form control autosizing, one that worked on multiple types of form controls (inputs, textareas, even select menus).It’s been developed by Lea Verou
You can also use it as a bookmarklet, to autosize form controls on an existing page, if a form is bothering you with its poor usability.
Stretchy has a spartan API, since in most cases you don’t need to call it at all. Stretchy works via event delegation and detects new elements via mutation observers, so you do not need to call any API methods for adding new elements via scripting
