How to filter elements

Learn how to filter DIV elements based on class names.

Create filterable DIV elements

Step 1 - Add HTML:

<!-- Control buttons -->
<div id="myBtnContainer">
  <button class="btn active" onclick="filterSelection('all')"> Show all</button>
  <button class="btn" onclick="filterSelection('cars')"> Cars</button>
  <button class="btn" onclick="filterSelection('animals')"> Animals</button>
  <button class="btn" onclick="filterSelection('fruits')"> Fruits</button>
  <button class="btn" onclick="filterSelection('colors')"> Colors</button>
</div>
<!-- Filterable elements. Please note that some have multiple class names (if they belong to multiple categories, these class names can be used) -->
<div class="container">
  <div class="filterDiv cars">BMW</div>
  <div class="filterDiv colors fruits">Orange</div>
  <div class="filterDiv cars">Volvo</div>
  <div class="filterDiv colors">Red</div>
  <div class="filterDiv cars">Ford</div>
  <div class="filterDiv colors">Blue</div>
  <div class="filterDiv animals">Cat</div>
  <div class="filterDiv animals">Dog</div>
  <div class="filterDiv fruits">Melon</div>
  <div class="filterDiv fruits animals">Kiwi</div>
  <div class="filterDiv fruits">Banana</div>
  <div class="filterDiv fruits">Lemon</div>
  <div class="filterDiv animals">Cow</div>
</div>

Step 2 - Add CSS:

.container {
  overflow: hidden;
}
.filterDiv {
  float: left;
  background-color: #2196F3;
  color: #ffffff;
  width: 100px;
  line-height: 100px;
  text-align: center;
  margin: 2px;
  display: none; /* Default hidden */
}
/* Add the "show" class to the filtered elements */
.show {
  display: block;
}
/* Set the style of the button */
.btn {
  border: none;
  outline: none;
  padding: 12px 16px;
  background-color: #f1f1f1;
  cursor: pointer;
}
/* Add light gray background when mouse hovers */
.btn:hover {
  background-color: #ddd;
}
/* Add dark background to the active button */
.btn.active {
  background-color: #666;
  color: white;
}

Step 3 - Add JavaScript:

filterSelection("all")
function filterSelection(c) {
  var x, i;
  x = document.getElementsByClassName("filterDiv");
  if (c == "all") c = "";
  // Add the "show" class (display:block) to filtered elements and remove the "show" class from unselected elements
  for (i = 0; i < x.length; i++) {
    w3RemoveClass(x[i], "show");
    if (x[i].className.indexOf(c) > -1) w3AddClass(x[i], "show");
  }
}
// Show filtered elements
function w3AddClass(element, name) {
  var i, arr1, arr2;
  arr1 = element.className.split(" ");
  arr2 = name.split(" ");
  for (i = 0; i < arr2.length; i++) {
    if (arr1.indexOf(arr2[i]) == -1) {
      element.className += " " + arr2[i];
    }
  }
}
// Hide unselected elements
function w3RemoveClass(element, name) {
  var i, arr1, arr2;
  arr1 = element.className.split(" ");
  arr2 = name.split(" ");
  for (i = 0; i < arr2.length; i++) {
    while (arr1.indexOf(arr2[i]) > -1) {
      arr1.splice(arr1.indexOf(arr2[i]), 1);
    }
  }
  element.className = arr1.join(" ");
}
// Add the active class to the current control button (highlight it)
var btnContainer = document.getElementById("myBtnContainer");
var btns = btnContainer.getElementsByClassName("btn");
for (var i = 0; i < btns.length; i++) {
  btns[i].addEventListener("click", function() {
    var current = document.getElementsByClassName("active");
    current[0].className = current[0].className.replace(" active", "");
    this.className += " active";
  });
}

Try It Yourself