JavaScript SideNav OneButton切换

Question

我设法让sidenav打开但无法让它关闭。我已经读过使用条件法是要走的路，但是这里没有做它应该做的事情。

这是我的代码：

var sidenav = document.getElementById("sidenav");
var page = document.getElementById("page");

function togNav() {
  if (sidenav.style.width = '0px') {
    sidenav.style.width = "200px";
    page.style.marginLeft = "200px";
  } else {
    sidenav.style.width = "0px";
    page.style.marginLeft = "0px";
  }
}

body {
  margin: 0;
  padding: 0;
}

.openbtn {
  background: none;
  border: none;
  outline: none;
  cursor: pointer;
}

#bar {
  width: 25px;
  height: 3px;
  margin: 6px;
  background: #999;
  border-radius: 5px;
}

.sidenav {
  height: 100%;
  width: 0px;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: #eee;
  overflow-x: hidden;
  transition: 0.5s;
}

.sidenav ul {
  margin: 0;
  padding: 0;
}

.sidenav li {
  list-style-type: none;
}

.sidenav a {
  color: #555;
  display: block;
  padding: 15px 0px 15px 75px;
  text-decoration: none;
  border-bottom: 0.1px #ddd solid;
  font-weight: 300;
  font-family: helvetica neue;
}

.sidenav a:hover {
  background: #ddd;
}

#page {
  margin-left: 0px;
  transition: 0.5s;
}

<div class="sidenav" id="sidenav">
  <ul>
    <li><a href="#">Link 1</a></li>
    <li><a href="#">Link 2</a></li>
    <li><a href="#">Link 3</a></li>
    <li><a href="#">Link 4</a></li>
    <li><a href="#">Link 5</a></li>
  </ul>
</div>
<div id="page">
  <button id="openbtn" class="openbtn" onclick="togNav()">
    <div id="bar"></div>
    <div id="bar"></div>
    <div id="bar"></div>
  </button>
</div>

Answer 1

如果情况有误。您使用的是=（作业），而是使用==进行比较

var sidenav = document.getElementById("sidenav");
var page = document.getElementById("page");

function togNav() {
  if (sidenav.style.width == '0px') { // here
    sidenav.style.width = "200px";
    page.style.marginLeft = "200px";
  } else {
    sidenav.style.width = "0px";
    page.style.marginLeft = "0px";
  }
}

body {
  margin: 0;
  padding: 0;
}

.openbtn {
  background: none;
  border: none;
  outline: none;
  cursor: pointer;
}

#bar {
  width: 25px;
  height: 3px;
  margin: 6px;
  background: #999;
  border-radius: 5px;
}


.sidenav {
  height: 100%;
  width: 0px;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: #eee;
  overflow-x: hidden;
  transition: 0.5s;
}

.sidenav ul {
  margin: 0;
  padding: 0;
}

.sidenav li {
  list-style-type: none;
}

.sidenav a {
  color: #555;
  display: block;
  padding: 15px 0px 15px 75px;
  text-decoration: none;
  border-bottom: 0.1px #ddd solid;
  font-weight: 300;
  font-family: helvetica neue;
}

.sidenav a:hover {
  background: #ddd;
}

#page {
  margin-left: 0px;
  transition: 0.5s;
}

<div class="sidenav" id="sidenav">
  <ul>
    <li><a href="#">Link 1</a></li>
    <li><a href="#">Link 2</a></li>
    <li><a href="#">Link 3</a></li>
    <li><a href="#">Link 4</a></li>
    <li><a href="#">Link 5</a></li>
  </ul>
</div>
<div id="page">
  <button id="openbtn" class="openbtn" onclick="togNav()">
    <div id="bar"></div>
    <div id="bar"></div>
    <div id="bar"></div>
  </button>
</div>