How to enable live preview for js in brackets?

Question

Adobe

There is such a video (short)
In it, starting from 1 minute 15 seconds. approximately the author opens the files as I understood from the gidhab and changes the settings so that the live preview would work for js. I just didn't understand how he opened these files. Maybe someone will tell?
And I was also interested in such a thing, the author pulls the mouse at 45 seconds and it smoothly changes the value, I have long wanted such a function. If there is a video, then it can be turned on somehow. Tell me how?

Answer 1

1) He opened the downloaded repository locally on the machine. How to enable LP mode is described in detail here .
2) Kind of like holding alt. Can install this