Detect Scroll Direction ?

[sadeghbarati]

when use smooth-scrollbar how to detect scroll direction from a fixed element ?

[idiotWu]

let lastOffset = null;

scrollbar.addListener(({ offset }) => {
  if (!lastOffset) {
    lastOffset = offset;
    return;
  }

  const dir = [];

  if (offset.y < lastOffset.y) {
    dir[0] = 'up';
  } else if (offset.y > lastOffset.y) {
    dir[0] = 'down';
  } else {
    dir[0] = 'still';
  }

  if (offset.x < lastOffset.x) {
    dir[1] = 'left';
  } else if (offset.x > lastOffset.x) {
    dir[1] = 'right';
  } else {
    dir[1] = 'still';
  }

  lastOffset = offset;

  switch(dir[0]) {
    case 'up':
    case 'down':
    case 'still':
  }

  switch(dir[1]) {
    case 'left':
    case 'right':
    case 'still':
  }
});

[anuragsr]

Why did you remove the direction property in status variable?

[idiotWu]

@anuragsr because it's not necessary in most cases.

[anuragsr]

@idiotWu Ok I guess you have your reasons. Nice library btw! I just feel that the scroll direction is a pretty handy property to have, many uses for animations :)