javascript - Change image while scrolling the mouse wheel - 


var myimages=[    "images/dad.png",    "images/terminal.png",    "images/hi.png",    "images/hengameh.png",    "images/shrinedefense.png"  ]  var slideshow=document.getelementbyid("slideshowers")  var nextslideindex=0  function rotateimage(e){    var evt=window.event || e    var delta=evt.detail? evt.detail*(-120) : evt.wheeldelta    nextslideindex=(delta<=-120)? nextslideindex+1 : nextslideindex-1    nextslideindex=(nextslideindex<0)? myimages.length-1 : (nextslideindex>myimages.length-1)? 0 : nextslideindex    slideshow.src=myimages[nextslideindex]    if (evt.preventdefault)      evt.preventdefault()    else      return false  }  var mousewheelevt=(/firefox/i.test(navigator.useragent))? "dommousescroll" : "mousewheel"    if (slideshow.attachevent)    slideshow.attachevent("on"+mousewheelevt, rotateimage)  else if (slideshow.addeventlistener)    slideshow.addeventlistener(mousewheelevt, rotateimage, false)
<img id="slideshowers" class="cover-images" src="http://www.ammaryar.ir/images/dad.png" />

hi, want change image, while scrolling mouse wheel. can find want in following link: http://www.ammaryar.ir there lantern on right side, have 4 lantern different colors. want change these lanterns while scrolling mouse wheel. did something, it's not working properly. if move mouse on lantern picture , trying scroll, images change random , repeat. don't change randomly , repeat, have 5 menu tabs , each menu have specific image while scroll mouse wheel.

const pageheight = document.documentelement.scrollheight - window.innerheight,        imgelement = document.getelementbyid('img'),        images     = ['http://lorempixel.com/400/200/city/1',                     'http://lorempixel.com/400/200/city/2',                     'http://lorempixel.com/400/200/city/3',                     'http://lorempixel.com/400/200/city/4'];  let   lastimage  = 0;    document.addeventlistener('scroll', () => {    let index = parseint(document.documentelement.scrolltop / pageheight * images.length);    index = math.min(index, images.length - 1); // prevent few pixel overflow      if (index !== lastimage) { // if need display different image      lastimage = index;      imgelement.src = images[lastimage];    }  });
body {    height: 700vh;    margin: 0;  }  img {    position: fixed;    top: 0;  }
<img id="img" src="http://lorempixel.com/400/200/city/1"/>

quoting myself another answer:

  • document.documentelement.scrollheight - window.innerheight height interested in. height of entire document reduced height of viewport. why need reduction? because whatever our current scroll position, never scroll out of document, i.e. see portion of , portion equals viewport's height.
  • document.documentelement.scrolltop / pageheight give our scroll position relatively document's height, i.e. how many percent of document have scrolled. number in range 0 1, interested in range 0 4, hence multiplying.

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