CODEWITHSUNDEEP
javascriptmouseeventkeyboard-eventsscroll-snapanimateplus
Tzar
Tzar

Reputation: 4789

Conflict when simultaneously using keyboard events for scrolling and CSS scroll snapping

You can horizontally scroll my demo page by pressing Space Bar, Page Up / Page Down and Left Arrow / Right Arrow keys. You can also snap scroll with a mouse or trackpad.

But only one or the other works.

Is there a way that keyboard events and CSS scroll snapping can coexist? What am I missing? Any help would be really appreciated, since I’ve been struggling with this problem for over a week.

Check out my demo on CodePen

(Please uncomment the relevant piece of CSS code to enable the scroll snapping effect in order to see that keyboard shortcuts stop working.)

import animate from "https://cdn.jsdelivr.net/npm/animateplus@2/animateplus.js"

const sections = Array.from(document.querySelectorAll("section")).sort(
  (s1, s2) => {
    return s1.getBoundingClientRect().left - s2.getBoundingClientRect().left
  }
)

const getSectionInView = () => {
  const halfWidth = window.innerWidth / 2
  const index = sections.findIndex(
    section =>
      section.getBoundingClientRect().left <= halfWidth &&
      section.getBoundingClientRect().right > halfWidth
  )
  return index
}

const getNextSection = dir => {
  const sectionInViewIndex = getSectionInView()
  const nextIndex = sectionInViewIndex + dir
  const numSections = sections.length
  const nextSectionIndex =
    nextIndex < 0 || nextIndex >= numSections ? sectionInViewIndex : nextIndex
  return sections[nextSectionIndex]
}

const container = document.scrollingElement

const animateScroll = dir => {
  const from = container.scrollLeft
  const { left } = getNextSection(dir).getBoundingClientRect()
  return progress => (container.scrollLeft = from + progress * left)
}

window.onload = () => {
  document.body.onkeydown = event => {
    switch (event.key) {
      case " ": // Space Bar
      case "PageDown":
      case "ArrowRight": {      
        animate({
          easing: "out-quintic",
          change: animateScroll(1)
        })
        break
      }
      case "PageUp":
      case "ArrowLeft":  {      
        animate({
          easing: "out-quintic",
          change: animateScroll(-1)
        })
        break
      }
    }
  }
}

Note: I’m using a small and elegant module called Animate Plus for achieving the smooth scrolling animation.

Update: @Kostja’s solution works in Chrome, but not in Safari for Mac or iOS, and it’s crucial to me that it works in Safari.

Upvotes: 13

Views: 1331

Answers (2)

kostja
kostja

Reputation: 355

I guess there is not, the css overwrites the javascript. But you can simply add wheel eventlistener like: 

window.addEventListener("wheel", function() {
    if(event.deltaY > 0){
      animate({
        easing: "out-quintic",
        change: animateScroll(1)
      })      
    }
      if(event.deltaY < 0){
      animate({
        easing: "out-quintic",
        change: animateScroll(-1)
      })      
    }      
});

https://codepen.io/kostjaaa/pen/NWWVBKd

Upvotes: 4

Jay Z
Jay Z

Reputation: 17

window.onload = () => {
  window.addEventListener("wheel", () => {
    const direction = event.deltaY > 0 ? 1 : event.deltaY < 0 ? -1 : false;

    if (direction) {
      animate({
        easing: "out-quintic",
        change: animateScroll(direction)
      });
    }
  });

  document.body.onkeydown = event => {
    switch (event.key) {
      case " ": // Space Bar
      case "PageDown":
      case "ArrowRight": {
        animate({
          easing: "out-quintic",
          change: animateScroll(1)
        });
        break;
      }
      case "PageUp":
      case "ArrowLeft": {
        animate({
          easing: "out-quintic",
          change: animateScroll(-1)
        });
        break;
      }
    }
  };
};

This should work.

https://codepen.io/JZ6/pen/XWWQqRK

Upvotes: 0

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