What is the name of the image format?

Question

JavaScript

I forgot, and neither remember nor formulate Google.
A tricky format for bitmaps that can be stretched without loss of quality. In fact, in it we create several areas - the borders, which always remain themselves, and the central part, which is just stretched. Often used in interfaces, for example, for buttons, I also saw it was used to make the background "scroll".
And, at the same time, are there libraries for js to work with it?

Answer 1

9-patch
https://github.com/chrislondon/9-patch-Image-for-W...

Answer 2

usually all the same is done on the principle of sprites with png / bmp.