javascript - Resizing logo when scrolling -


i have used following code change size of logo when scrolling down page. 

$(document).on('scroll', function() {    if ($(document).scrolltop() >= 10) {      $('.logo img').css('width', '50px');    } else {      $('.logo img').css('width', '');    }  });
.nav {    position: fixed top: 0;    z-index: 1;    width: 100%;  }    .nav .logo {    position: fixed;    text-align: left;    z-index: 2;    top: 0;    overflow: hidden;    opacity: .5;  }    .container {    padding-top: 120px;    height: 500px;  }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>  <div class="nav">    <div class="logo">      <a href="index.html"><img src="http://placehold.it/100x100" alt="" /></a>    </div>  </div>  <div class="container">    lorem ipsum  </div>

i transition smooth large small.

https://jsfiddle.net/sl89qxcx/

is there can add achieve smooth transition?

the best way achieve use css transitions, hardware accelerated, , better separation of concerns. can toggle animation adding/removing class in js.

the important part add both width , transition rule default state of .logo img element. can amend width in added class. try this:

$(document).on('scroll', function() {    $('.logo img').toggleclass('small', $(document).scrolltop() >= 10);  });
.nav {    position: fixed top: 0;    z-index: 1;    width: 100%;  }    .nav .logo {    position: fixed;    text-align: left;    z-index: 2;    top: 0;    overflow: hidden;    opacity: .5;  }    .nav .logo img {    width: 100px;    transition: width 0.3s;  }    .nav .logo img.small {    width: 50px;  }    .container {    padding-top: 120px;    height: 500px;  }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>  <div class="nav">    <div class="logo">      <a href="index.html"><img src="http://placehold.it/100x100" alt="" /></a>    </div>  </div>  <div class="container">    lorem ipsum  </div>


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