Answers for "js create scroll down"

smooth scroll css

html {
  scroll-behavior: smooth;
}

/* No support in IE, or Safari
You can use this JS polyfill for those */
http://iamdustan.com/smoothscroll/

how to smooth scroll in javascript

window.scrollTo({ top: 900, behavior: 'smooth' })

javascript scroll down

window.scrollTo(300, 500);	//X=300 and Y=500