为什么我的侧边栏媒体查询不能在Javascript中运行？

Question

我有一个侧边栏，使用桌面视图上的javscript滑出250px。说到移动视图，我希望侧边栏占据100％的宽度。我试图在Javascript中使用媒体查询但不管我做了什么改变它似乎覆盖了我在桌面视图上的侧边栏的样式。

HTML

 <nav class="navbar">
  <div id="toggle-btn" class="sidemenu-btn">
    <i class="fas fa-bars"></i>
  </div>
  <div id="toggle-nav" class="navbar-items animated fadeInLeft delay-1s">
    <a href="#home">Home</a>
    <a href="#about-me">About</a>
    <a href="#my-skills">Skills</a>
    <a href="#my-portfolio">Portfolio</a>
    <a href="#contact-me">Contact</a>
  </div>
</nav>

CSS

 .navbar {
      height: 100%;
      width: 0;
      position: fixed;
      background: #141313;
    }

    .navbar .sidemenu-btn {
     font-size: 2.5rem;
     padding: 3rem 0;
     text-align: center;
     margin-left: 1rem;
     cursor: pointer;
     color: #141313;
    }

    .navbar .navbar-items {
    display: flex;
    flex-direction: column;
    text-align: center;
    display: none;
    margin-left: 1rem;
    }

   .navbar .navbar-items a {
    text-decoration: none;
    color: white;
    padding: 1.2rem 0;
    font-weight: 400;
    font-size: 1.2rem;
    text-transform: uppercase;
    }

   .navbar .navbar-items a:hover {
    text-decoration: line-through;
   }

@media screen and (max-width: 768px) {

.navbar {
  position: relative;
}


}

JS

const toggleBtn = document.querySelector("#toggle-btn");
const toggleNav = document.querySelector(".navbar");
const togglenavItems = document.querySelector('.navbar-items');

toggleBtn.addEventListener("click", sideMenu);
toggleBtn.addEventListener("click", mediaQuery);


    function sideMenu() {
  if (toggleNav.style.width === "250px") {
    toggleNav.style.width = "0px";
  } else {
    toggleNav.style.width = "250px";
  }

}



function mediaQuery() {
  const x = window.matchMedia('(max-width: 768px)');
  const y = document.querySelector('.navbar');

  if (x.matches && y.style.width === "100%") {
    y.style.width = "0px";

  } else {
    y.style.width = "100%";

  }



}

Answer 1

媒体查询可以完成工作。你不需要js来改变navbar-items的宽度。看到这个

const toggleBtn = document.querySelector("#toggle-btn");
const toggleNav = document.querySelector(".navbar");
const togglenavItems = document.querySelector('.navbar-items');

toggleBtn.addEventListener("click", sideMenu);

function sideMenu() {
  toggleNav.classList.toggle('open');
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
}

.navbar {
    height: 100%;
    width: 100%;
    position: fixed;

  }

  .sidemenu-btn {
     font-size: 2.5rem;
     padding: 0;
     text-align: center;
     cursor: pointer;
     color: green;
     position: absolute;
     right: 20px;
     top: 20px;
  }

  .navbar-items {
    display: flex;
    flex-direction: column;
    text-align: center;
    width: 250px;
    height: 100%;
    padding-left: 1rem;
    background: #141313;
    transition: all .5s ease;
  }

 .navbar .navbar-items a {
    text-decoration: none;
    color: white;
    padding: 1.2rem 0;
    font-weight: 400;
    font-size: 1.2rem;
    text-transform: uppercase;
  }

 .navbar .navbar-items a:hover {
  text-decoration: line-through;
 }


@media (max-width: 768px) {
  .navbar-items {
    width: 100%;
  }
}

.navbar.open .navbar-items {
  width: 0;
}

<nav class="navbar">
  <div id="toggle-btn" class="sidemenu-btn">
    <i class="fas fa-bars"></i>
    Toggle
  </div>
  <div id="toggle-nav" class="navbar-items animated fadeInLeft delay-1s">
    <a href="#home">Home</a>
    <a href="#about-me">About</a>
    <a href="#my-skills">Skills</a>
    <a href="#my-portfolio">Portfolio</a>
    <a href="#contact-me">Contact</a>
  </div>
</nav>

只需添加媒体查询即可更改元素的宽度，无需签入js

@media (max-width: 768px) {
 .navbar-items {
   width: 100%;
 }
}

添加将在.open上添加的.navbar类并将触发转换

.navbar.open .navbar-items {
  width: 0;
}

你的js现在已经简化了

const toggleBtn = document.querySelector("#toggle-btn");
const toggleNav = document.querySelector(".navbar");

toggleBtn.addEventListener("click", sideMenu);

function sideMenu() {
  toggleNav.classList.toggle('open');
}

Answer 2

使用CSS可以更轻松地控制它在移动/桌面上的外观，而JS只是处理逻辑。以下将修复样式差异，并使您的JS更容易导航。

CSS

 .navbar{
   width: 250px;
   height: 100%;
   position: fixed;
   background: #141313;
 }     
 .navHidden{
  width: 0px !important;
 }
 /* smaller screen size */
 @media screen and (max-width:768px) {
   .navbar{
     width: 100%;
   }
 }

HTML

<nav class="navbar navHidden">

JS

function sideMenu() {
  toggleNav.classList.toggle("navHidden")
}

嫣

在您提供的代码中，单击切换按钮，您将导航栏的宽度设置为250px，但随后它将传递到您的下一个功能，无论屏幕大小如何，它都会在每个案例中将其交换为100％ ，所以你写的切换功能永远不会奏效。