Avoid scroll in main content when support div is open - mobile only

Question

I have a page where i put a small support windows represented by a div. When the user opens it, he should not be able to scroll in the main content that is behind.

The user should only be able to scroll inside of this div if the content is bigger than the screen.

How I can avoid the scrolling in the main content?

So far I have:

(function() {
  var viewport = document.createElement("meta");
  viewport.setAttribute('name', 'viewport');
  viewport.setAttribute('content', 'width=device-width, initial-scale=1');
  document.getElementsByTagName('head')[0].appendChild(viewport);


  var support = document.getElementById("support");
  support.addEventListener("click", function() {
    if (support.classList.contains('is-open')) {
      support.classList.remove('is-open');
    } else {
      support.classList.add('is-open');
    }
  });
})();

.support {
  position: fixed;
  bottom: 0;
  right: 0;
  width: 200px;
  border: 1px solid #ccc;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
}

.support .support-header {
  background-color: blue;
  cursor: pointer;
}

.support .support-header h2 {
  margin: 0;
  padding: 5px 10px;
  color: white;
  font-size: 15px;
}

.support .support-content {
  display: none;
  background-color: #f3f5f8;
  padding: 5px;
}

.support.is-open {
  max-width: 100%;
}

.support.is-open .support-content {
  display: block;
}

<div class="container">
  <section>
    <h2>What is Lorem Ipsum?</h2>
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
  </section>
  <div class="support" id="support">
    <div class="support-header">
      <h2>Support</h2>
    </div>
    <div class="support-content">
      <p>It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content
        here, content here', making it look like readable English.</p>
    </div>
  </div>
</div>

Answer 1

You can simply set overflow: hidden for the body then. Note that you can use classList.toggle('is-open') instead of the if else like shown below.

(function() {
  var support = document.getElementById("support");
  support.addEventListener("click", function() {
    document.body.classList.toggle('is-open');
    support.classList.toggle('is-open');
    /*
if (support.classList.contains('is-open')) {
      support.classList.remove('is-open');
      document.body.classList.remove('is-open');
    } else {
      support.classList.add('is-open');
      document.body.classList.add('is-open');
    }*/
  });
})();

body.is-open {
  overflow: hidden;
}

.support {
  position: fixed;
  bottom: 0;
  right: 0;
  width: 200px;
  border: 1px solid #ccc;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
}

.support .support-header {
  background-color: blue;
  cursor: pointer;
}

.support .support-header h2 {
  margin: 0;
  padding: 5px 10px;
  color: white;
  font-size: 15px;
}

.support .support-content {
  display: none;
  background-color: #f3f5f8;
  padding: 5px;
}

.support.is-open {
  max-width: 100%;
}

.support.is-open .support-content {
  display: block;
}

<div class="container">
  <section>
    <h2>What is Lorem Ipsum?</h2>
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
    v
    <p>
      Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has
      survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
      publishing software like Aldus PageMaker including versions of Lorem Ipsum
    </p>
    <h2>
      Where does it come from?
    </h2>
    <p>
      Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up
      one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus
      Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line
      in section 1.10.32.
    </p>
    <p>The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions
      from the 1914 translation by H. Rackham.</p>
  </section>
  <div class="support" id="support">
    <div class="support-header">
      <h2>Support</h2>
    </div>
    <div class="support-content">
      <p>It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content
        here, content here', making it look like readable English.</p>
    </div>
  </div>
</div>