script.js

/* Set the width of the side navigation to 250px and the left margin of the page content to 250px and add a black background color to body */
function openNav() {
  document.getElementById("mySidenav").style.width = "250px";
  document.getElementById("main").style.marginLeft = "250px";
  document.body.style.backgroundColor = "rgba(0,0,0,0.4)";
}
/* Set the width of the side navigation to 0 and the left margin of the page content to 0, and the background color of body to white */
function closeNav() {
  document.getElementById("mySidenav").style.width = "0";
  document.getElementById("main").style.marginLeft = "0";
  document.body.style.backgroundColor = "white";
}


filterSelection("all") // Execute the function and show all columns
function filterSelection(c) {
  var x, i;
  x = document.getElementsByClassName("column");
  if (c == "all") c = "";
  // Add the "show" class (display:block) to the filtered elements, and remove the "show" class from the elements that are not selected
  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 elements that are not selected
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 active class to the current button (highlight it)
var btnContainer = document.getElementById("myBtnContainer");
var btns = btnContainer.getElementsByClassName("btnbtn");
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";
  });
}