JavaScript tips for real projects

How to Detect Word Wrap in a Textarea with JavaScript (No Libraries)

A textarea will not tell you when its text wraps. There is no wrap event, no callback, nothing. The browser draws the line break visually and moves on, and textarea.value stays exactly the same string you typed. If you need to know when content has flowed onto a new visual row, you have to measure it yourself, and the cleanest way to do that is with a hidden mirror element. This guide on how to detect word wrap in textarea JavaScript walks through the exact technique I use in production, with a working example you can paste in.