Another example is trying to implement a text-editor in the browser. Yes it can be done, but the standard component for text-editors is TextArea which is not much to write home about.
An example big issue I faced creating my own editor was getting the caret follow my mouse-clicks and key-presses. Then trying to highlight matching parenthesis. I know it is doable because I did it but I had to spend a lot of time on it and I'm not quite happy with the end-result. A standard high-quality text-editor component should be part of the web-platform but is not.
Yes, I had to do something similar using the contenteditable, a giant issue is that the browsers differ a lot(I had a lot of issue with the selections/ranges differing a lot)
An example big issue I faced creating my own editor was getting the caret follow my mouse-clicks and key-presses. Then trying to highlight matching parenthesis. I know it is doable because I did it but I had to spend a lot of time on it and I'm not quite happy with the end-result. A standard high-quality text-editor component should be part of the web-platform but is not.